文章
Miss Chen
2018年07月31日
Description: This plant is a winter or spring annual that becomes 4-10" tall. It has a small tuft of erect to ascending leafy stems; these stems are light green to dark purple, terete, and hairy. Along each stem, there are pairs of sessile opposite leaves at intervals. Individual leaves are up to ¾" long and about half as much across; they are medium green, bluntly ovate, broadly oblong, or obovate with smooth margins. Both the lower and upper surfaces of each leaf are covered with hairs. The hairs on the stems and leaves may have a sticky texture from minute glandular secretions.
Each stem terminates in a dense cluster of flowers; in addition, individual or small clusters of flowers may develop from the axils of the upper leaves. Each small flower is about ¼" across, consisting of 5 white petals, 5 green sepals, 10 stamens, and a pistil with 5 styles. The tips of the petals are notched. The lanceolate sepals have long forward-pointing hairs and membranous margins. The hairy pedicel of each flower is no longer than 5 mm. (1/5") in length, even when it has transformed into a seed capsule. The blooming period occurs from mid-spring to early summer and lasts about 3-4 weeks. Each flower transforms into a cylindrical seed capsule that is up to twice the length of the persistent sepals. This seed capsule is membranous along the sides and open at the apex, where there are 10 tiny teeth. At the bottom of this capsule, there are several tiny seeds. Each seed is obovoid or heart-shaped, somewhat flattened, and minutely pebbly on the outer surface. The root system is shallow and fibrous. This plant spreads by reseeding itself; it often forms colonies in favorable habitats.
Cultivation: This little weed prefers partial to full sun and moist to slightly dry conditions. It is often found in soil containing loam, clay-loam, or other material. This species can invade lawns to some extent.
Range & Habitat: Glomerate Mouse-Eared Chickweed is occasional throughout Illinois (see Distribution Map), where it is not native. Habitats include openings in rocky woodlands, grassy meadows, lawns, pastures, fallow fields, roadsides, and waste ground. Areas with a history of disturbance are preferred. This species is native to Eurasia.
Faunal Associations: The nectar and pollen of the flowers attract small bees (Halictid & others) and flies (Syrphid & others). The caterpillars of the moths Agrostis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave) feed on chickweeds. Among vertebrate animals, the Mourning Dove and various sparrows occasionally eat the seeds, while the foliage is eaten by the Cottontail Rabbit and Woodchuck.
Photographic Location: A lawn at a state park in west-central Indiana.
Comments: The distinctive characteristic of this chickweed is its dense cluster(s) of flowers. In particular, the pedicels of the flowers are the same length or shorter than the sepals (5 mm. or less). Several other species of chickweeds are similar in appearance, but at least some of their pedicels exceed 5 mm. in length (particularly when their flowers have transformed into seed capsules). The sepals of Glomerate Mouse-Eared Chickweed are somewhat unusual because they are covered with long forward-pointing hairs that may extend beyond their margins; other species of chickweed have sepals with shorter hairs. In general, the various species in the Cerastium genus are called "Mouse-Eared Chickweeds" because of the shape and hairiness of their leaves; these species usually have 10 stamens and 5 styles per flower. A scientific synonym of Glomerate Mouse-Eared Chickweed is Cerastium viscosum. Because of this defunct scientific name, this species is sometimes called "Clammy Mouse-Eared Chickweed."
Each stem terminates in a dense cluster of flowers; in addition, individual or small clusters of flowers may develop from the axils of the upper leaves. Each small flower is about ¼" across, consisting of 5 white petals, 5 green sepals, 10 stamens, and a pistil with 5 styles. The tips of the petals are notched. The lanceolate sepals have long forward-pointing hairs and membranous margins. The hairy pedicel of each flower is no longer than 5 mm. (1/5") in length, even when it has transformed into a seed capsule. The blooming period occurs from mid-spring to early summer and lasts about 3-4 weeks. Each flower transforms into a cylindrical seed capsule that is up to twice the length of the persistent sepals. This seed capsule is membranous along the sides and open at the apex, where there are 10 tiny teeth. At the bottom of this capsule, there are several tiny seeds. Each seed is obovoid or heart-shaped, somewhat flattened, and minutely pebbly on the outer surface. The root system is shallow and fibrous. This plant spreads by reseeding itself; it often forms colonies in favorable habitats.
Cultivation: This little weed prefers partial to full sun and moist to slightly dry conditions. It is often found in soil containing loam, clay-loam, or other material. This species can invade lawns to some extent.
Range & Habitat: Glomerate Mouse-Eared Chickweed is occasional throughout Illinois (see Distribution Map), where it is not native. Habitats include openings in rocky woodlands, grassy meadows, lawns, pastures, fallow fields, roadsides, and waste ground. Areas with a history of disturbance are preferred. This species is native to Eurasia.
Faunal Associations: The nectar and pollen of the flowers attract small bees (Halictid & others) and flies (Syrphid & others). The caterpillars of the moths Agrostis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave) feed on chickweeds. Among vertebrate animals, the Mourning Dove and various sparrows occasionally eat the seeds, while the foliage is eaten by the Cottontail Rabbit and Woodchuck.
Photographic Location: A lawn at a state park in west-central Indiana.
Comments: The distinctive characteristic of this chickweed is its dense cluster(s) of flowers. In particular, the pedicels of the flowers are the same length or shorter than the sepals (5 mm. or less). Several other species of chickweeds are similar in appearance, but at least some of their pedicels exceed 5 mm. in length (particularly when their flowers have transformed into seed capsules). The sepals of Glomerate Mouse-Eared Chickweed are somewhat unusual because they are covered with long forward-pointing hairs that may extend beyond their margins; other species of chickweed have sepals with shorter hairs. In general, the various species in the Cerastium genus are called "Mouse-Eared Chickweeds" because of the shape and hairiness of their leaves; these species usually have 10 stamens and 5 styles per flower. A scientific synonym of Glomerate Mouse-Eared Chickweed is Cerastium viscosum. Because of this defunct scientific name, this species is sometimes called "Clammy Mouse-Eared Chickweed."
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文章
Miss Chen
2018年07月30日
Description: This plant is a winter or spring annual about 4-16" tall that sometimes branches from the base, forming a tuft of leafy stems. Each erect to ascending stem is light green to pale purplish green, terete, and evenly glandular-pubescent. Several pairs of opposite leaves occur along each stem; sometimes tufts of smaller leaves develop from the axils of the lower opposite leaves. These leaves are up to 1" long and 1/5" (5 mm.) across; they are linear, linear-oblong, or oblong, and sessile against their stems. Each leaf is hairless on the upper surface with a single prominent vein; the lower surface is also hairless, except for some glandular hairs along the central vein. The leaf margins are smooth and ciliate.
Each stem terminates in a corymb (flat-headed cluster) or compound corymb of flowers. The peduncle of each corymb is similar to the stem, except that it has a pair of leafy bracts at its base; it can be several inches long. Compound corymbs have branched ascending peduncles. Each flower is up to ¼" across; it has 5 white petals, 5 green sepals, 10 stamens, and 3 tiny white styles at the apex of the light green ovary. The petals are cleft at their tips, while the sepals are glandular-pubescent. The pedicel of each flower is up to ½" long and glandular-pubescent. The leafy bracts are linear-lanceolate to ovate, glandular-pubescent on their undersides, and slightly membranous along their margins at maturity; they are smaller in size than the leaves (½" long or less). The blooming period occurs during the late spring and lasts about 3 weeks. There is no noticeable floral scent. Each flower is replaced by a cylindrical seed capsule that is up to 10 mm. (3/8") long. At maturity, this seed capsule becomes membranous and open at its apex; there are 6 small teeth along its upper rim. There are numerous small seeds within each capsule; each seed is pale brown, minutely warty, ovoid-obovoid in shape, and somewhat flattened. The root system consists of a slender branching taproot with fine fibrous roots. This plant spreads by reseeding itself and occasionally forms colonies.
Cultivation: Typical growing conditions consist of full sunlight and average levels of moisture. Three-styled Chickweed adapts readily to loam or clay-loam soil; sandy or gravelly soil may be tolerated as well. Because this chickweed is taller and more erect than most, regular mowing may inhibit its spread.
Range & Habitat: The adventive Three-Styled Chickweed is a rare weed in Illinois; it has been observed in only a few counties of south-central and east-central Illinois (see Distribution Map). This species is native to southern Europe and parts of Asia. The earliest collection of this species in the United States occurred in the state of Washington during the 1960's. Since that time, it has been observed in several other states (both eastern & western) and appears to be spreading. Habitats include disturbed areas with low grassy or weedy vegetation and the upper slopes of ditches. Recent construction activity mayClose-up of Flower have introduced this species to Champaign County in Illinois.
Faunal Associations: This information applies to chickweeds, both native and introduced, that are typically found in sunny meadows and similar habitats. The nectar and pollen of the flowers attract small bees (Halictid & others) and flies (Syrphid & others). The caterpillars of the moths Agrostis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave) feed on chickweeds. Among vertebrate animals, the seeds are a source of food for the Mourning Dove and various sparrows, while the foliage is occasionally eaten by the Cottontail Rabbit.
Photographic Location: The upper slope of a drainage ditch in Urbana, Illinois. If the photograph of the flower close-up is examined closely, it is possible to see the 3 tiny white styles; they are surrounded by the yellow anthers of the stamens.
Comments: Among Cerastium spp. (Mouse-Eared Chickweeds), this chickweed is highly unusual because its flowers have 3 styles, rather than 5 styles. This characteristic is more typical of Stellaria spp. (Chickweeds). However, other characteristics of its flowers (e.g., the presence of 10 stamens & the shape of its petals) and the even pubescence of its stems are more typical of the Mouse-Eared Chickweeds. Three-Styled Chickweed is a little taller than most of these species and its leaves are more slender. Otherwise, it is rather ordinary looking. Another common name is Doubtful Chickweed, which is derived from the scientific name.
Each stem terminates in a corymb (flat-headed cluster) or compound corymb of flowers. The peduncle of each corymb is similar to the stem, except that it has a pair of leafy bracts at its base; it can be several inches long. Compound corymbs have branched ascending peduncles. Each flower is up to ¼" across; it has 5 white petals, 5 green sepals, 10 stamens, and 3 tiny white styles at the apex of the light green ovary. The petals are cleft at their tips, while the sepals are glandular-pubescent. The pedicel of each flower is up to ½" long and glandular-pubescent. The leafy bracts are linear-lanceolate to ovate, glandular-pubescent on their undersides, and slightly membranous along their margins at maturity; they are smaller in size than the leaves (½" long or less). The blooming period occurs during the late spring and lasts about 3 weeks. There is no noticeable floral scent. Each flower is replaced by a cylindrical seed capsule that is up to 10 mm. (3/8") long. At maturity, this seed capsule becomes membranous and open at its apex; there are 6 small teeth along its upper rim. There are numerous small seeds within each capsule; each seed is pale brown, minutely warty, ovoid-obovoid in shape, and somewhat flattened. The root system consists of a slender branching taproot with fine fibrous roots. This plant spreads by reseeding itself and occasionally forms colonies.
Cultivation: Typical growing conditions consist of full sunlight and average levels of moisture. Three-styled Chickweed adapts readily to loam or clay-loam soil; sandy or gravelly soil may be tolerated as well. Because this chickweed is taller and more erect than most, regular mowing may inhibit its spread.
Range & Habitat: The adventive Three-Styled Chickweed is a rare weed in Illinois; it has been observed in only a few counties of south-central and east-central Illinois (see Distribution Map). This species is native to southern Europe and parts of Asia. The earliest collection of this species in the United States occurred in the state of Washington during the 1960's. Since that time, it has been observed in several other states (both eastern & western) and appears to be spreading. Habitats include disturbed areas with low grassy or weedy vegetation and the upper slopes of ditches. Recent construction activity mayClose-up of Flower have introduced this species to Champaign County in Illinois.
Faunal Associations: This information applies to chickweeds, both native and introduced, that are typically found in sunny meadows and similar habitats. The nectar and pollen of the flowers attract small bees (Halictid & others) and flies (Syrphid & others). The caterpillars of the moths Agrostis venerabilis (Venerable Dart), Haematopis grataria (Chickweed Geometer), and Lobocleta ossularia (Drab Brown Wave) feed on chickweeds. Among vertebrate animals, the seeds are a source of food for the Mourning Dove and various sparrows, while the foliage is occasionally eaten by the Cottontail Rabbit.
Photographic Location: The upper slope of a drainage ditch in Urbana, Illinois. If the photograph of the flower close-up is examined closely, it is possible to see the 3 tiny white styles; they are surrounded by the yellow anthers of the stamens.
Comments: Among Cerastium spp. (Mouse-Eared Chickweeds), this chickweed is highly unusual because its flowers have 3 styles, rather than 5 styles. This characteristic is more typical of Stellaria spp. (Chickweeds). However, other characteristics of its flowers (e.g., the presence of 10 stamens & the shape of its petals) and the even pubescence of its stems are more typical of the Mouse-Eared Chickweeds. Three-Styled Chickweed is a little taller than most of these species and its leaves are more slender. Otherwise, it is rather ordinary looking. Another common name is Doubtful Chickweed, which is derived from the scientific name.
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文章
Miss Chen
2018年07月30日
Description: This herbaceous plant is a summer annual (in Illinois) that forms a low rosette during the spring, but by summer it bolts to become 1-4' tall. A typical plant is unbranched below and branched above with ascending lateral stems. The stems are light green to light yellowish tan, terete, glabrous, and stiff. Alternate leaves occur at intervals along these stems. These leaves are 2-6" long, ½-2" across, and stiff; they are lanceolate, lanceolate-oblong, ovate, or ovate-oblong in shape. The leaf bases are sessile or they clasp the stems. Leaf margins are mostly smooth (entire) with scattered yellow spines, although lower leaf margins are sometimes spineless and slightly dentate (although in some uncommon cultivars, all leaves may be spineless). Both the upper and lower surfaces of the leaves are dark green and glabrous; minute pubescence may occur along the lower surfaces of the central leaf veins.
Each upper stem terminates in 1-5 flowerheads. The flowerheads of each branch are usually clustered together on short peduncles. Each flowerhead is ¾-1½" across (excluding the outer phyllaries), consisting of 20-100 disk florets. These florets are ¾-1" in length, although their bases are hidden from view. The corollas of these florets are yellow to red (rarely white), narrowly cylindrical below, and 5-lobed above; these lobes are linear in shape and spreading. The styles are strongly exerted from the corollas. Around the base of the flowerhead, there are several outer phyllaries (floral bracts) up to 1½" long that are widely spreading and stiff; they are elliptic or lanceolate in shape, while their margins are smooth (entire) with scattered yellow spines. The surfaces of these outer bracts are dark green and glabrous. The inner phyllaries are mostly erect and appressed together; they are light green, ovate or lanceolate in shape, and covered with appressed hairs. The margins of the inner phyllaries are mostly smooth (entire) and ciliate, although their tips are spiny. However, in some uncommon cultivars, both outer and inner phyllaries are spineless. The blooming period occurs from mid-spring into the fall (in Illinois), lasting about 1-3 months. Afterwards, fertile florets are replaced by achenes. The achenes are 6-8 mm. long, white or light brown, oblanceoloid in shape, bluntly 4-angled, and often longitudinally striped. Usually the apices of these achenes lack tufts of hair, although in some uncommon cultivars short stiff bristles are present. The root system consists of a stout taproot up to 3-4' long and some lateral roots. This plant reproduces by reseeding itself.
Cultivation: Safflower adapts to full sun, mesic to dry conditions, and various kinds of soil, including those that contain loam, sandy loam, or clay-loam. It prefers cool to warm temperatures while in the rosette stage, and warm to hot temperatures after it bolts (a warm-temperate zone with long summer days, a long growing season, and adequate rainfall prior to the blooming period). In areas with high humidity or cool weather during the summer, this plant is vulnerable to a variety of fungal disease organisms. Because of the deep taproot, resistance to heat and drought is excellent.
Range & Habitat: The non-native Safflower uncommonly naturalizes in Illinois, occurring in Champaign County (see Distribution Map). However, the presence of this species within the state is probably under-reported. Because of its preference for areas with relatively low humidity, Safflower is cultivated primarily in the western half of the United States, where it more frequently naturalizes. In the eastern half of the United States (including Illinois), naturalized plants are typically found around bird feeders as Safflower is sometimes used as a source of bird seed. Naturalized plants can occur after birds inadvertently drop the seeds, or spill the seeds from a bird feeder. As a result, typically habitats in Illinois are unmowed areas around bird feeders, including vegetable gardens, flowerbeds, open spaces near shrubbery, and edges of yards. However, these naturalized plants rarely persist from one year to the next. Safflower was introduced into the United States during the early 20th century as an agricultural crop (as a source of vegetable oil and a dye for clothing or food). This plant is probably native to the eastern Mediterranean region and parts of southern and central Asia, where it has been cultivated for thousands of years.
Faunal Associations: Little specific information is available for the floral-faunal relationships of Safflower in North America. The flowers are cross-pollinated by bumblebees, honeybees, other long-tongued bees, and probably other insects with long mouth parts (e.g., butterflies & skippers). However, in the absence of cross-pollination, the flowers are self-fertile. Seed bugs (Lygus), aphids, leafhoppers, thrips, wireworms, and the larvae of some moths are reported to feed destructively on Safflower. Among vertebrate animals, some songbirds (e.g., Cardinals) and probably upland gamebrids feed on the seeds, which are sometimes used as a source of food in bird feeders. Prior to the blooming period, the foliage of Safflower is reportedly edible to sheep and, to a lesser extent, cattle. The suitability of the foliage as a source of forage depends in part on its level of spininess; this varies with different cultivars.
Photographic Location: A mulched bed near some shrubbery at the Anita Purves Nature Center in Urbana, Illinois.
Comments: Safflower is grown primarily as an agricultural crop in the western half of the United States and other parts of the world. The flowerheads are a source of red and yellow dyes for clothing and food (now largely replaced by synthetic dyes), while vegetable oil is derived from its seeds. Safflower oil is high in oleic and linoleic fatty acids, and it is used as a source for cooking oil, salad oil, industrial oil, biodiesel fuel, margarine, soap, cosmetics, oil-based paints, and varnishes. Roasted or fried hulled seeds are edible to humans, while unhulled raw seeds are used as a source of food for birds. Young foliage and meal from processed seeds are edible to livestock (e.g., cattle & sheep). The primary advantage of Safflower over other agricultural crops is its ability to adapt to hot dry climates. Because of the spines on its foliage and floral bracts, Safflower resembles thistles (Cirsium spp., Carduus spp.), but the corollas of its flowerheads are yellow to red, rather than pink or purple. Unlike thistles, the achenes of Safflower lack tufts of hair at their apices, except for some uncommon cultivars that have achenes with short bristles. In addition, the widely spreading and spiny floral bracts of Safflower have a distinctive appearance.
Each upper stem terminates in 1-5 flowerheads. The flowerheads of each branch are usually clustered together on short peduncles. Each flowerhead is ¾-1½" across (excluding the outer phyllaries), consisting of 20-100 disk florets. These florets are ¾-1" in length, although their bases are hidden from view. The corollas of these florets are yellow to red (rarely white), narrowly cylindrical below, and 5-lobed above; these lobes are linear in shape and spreading. The styles are strongly exerted from the corollas. Around the base of the flowerhead, there are several outer phyllaries (floral bracts) up to 1½" long that are widely spreading and stiff; they are elliptic or lanceolate in shape, while their margins are smooth (entire) with scattered yellow spines. The surfaces of these outer bracts are dark green and glabrous. The inner phyllaries are mostly erect and appressed together; they are light green, ovate or lanceolate in shape, and covered with appressed hairs. The margins of the inner phyllaries are mostly smooth (entire) and ciliate, although their tips are spiny. However, in some uncommon cultivars, both outer and inner phyllaries are spineless. The blooming period occurs from mid-spring into the fall (in Illinois), lasting about 1-3 months. Afterwards, fertile florets are replaced by achenes. The achenes are 6-8 mm. long, white or light brown, oblanceoloid in shape, bluntly 4-angled, and often longitudinally striped. Usually the apices of these achenes lack tufts of hair, although in some uncommon cultivars short stiff bristles are present. The root system consists of a stout taproot up to 3-4' long and some lateral roots. This plant reproduces by reseeding itself.
Cultivation: Safflower adapts to full sun, mesic to dry conditions, and various kinds of soil, including those that contain loam, sandy loam, or clay-loam. It prefers cool to warm temperatures while in the rosette stage, and warm to hot temperatures after it bolts (a warm-temperate zone with long summer days, a long growing season, and adequate rainfall prior to the blooming period). In areas with high humidity or cool weather during the summer, this plant is vulnerable to a variety of fungal disease organisms. Because of the deep taproot, resistance to heat and drought is excellent.
Range & Habitat: The non-native Safflower uncommonly naturalizes in Illinois, occurring in Champaign County (see Distribution Map). However, the presence of this species within the state is probably under-reported. Because of its preference for areas with relatively low humidity, Safflower is cultivated primarily in the western half of the United States, where it more frequently naturalizes. In the eastern half of the United States (including Illinois), naturalized plants are typically found around bird feeders as Safflower is sometimes used as a source of bird seed. Naturalized plants can occur after birds inadvertently drop the seeds, or spill the seeds from a bird feeder. As a result, typically habitats in Illinois are unmowed areas around bird feeders, including vegetable gardens, flowerbeds, open spaces near shrubbery, and edges of yards. However, these naturalized plants rarely persist from one year to the next. Safflower was introduced into the United States during the early 20th century as an agricultural crop (as a source of vegetable oil and a dye for clothing or food). This plant is probably native to the eastern Mediterranean region and parts of southern and central Asia, where it has been cultivated for thousands of years.
Faunal Associations: Little specific information is available for the floral-faunal relationships of Safflower in North America. The flowers are cross-pollinated by bumblebees, honeybees, other long-tongued bees, and probably other insects with long mouth parts (e.g., butterflies & skippers). However, in the absence of cross-pollination, the flowers are self-fertile. Seed bugs (Lygus), aphids, leafhoppers, thrips, wireworms, and the larvae of some moths are reported to feed destructively on Safflower. Among vertebrate animals, some songbirds (e.g., Cardinals) and probably upland gamebrids feed on the seeds, which are sometimes used as a source of food in bird feeders. Prior to the blooming period, the foliage of Safflower is reportedly edible to sheep and, to a lesser extent, cattle. The suitability of the foliage as a source of forage depends in part on its level of spininess; this varies with different cultivars.
Photographic Location: A mulched bed near some shrubbery at the Anita Purves Nature Center in Urbana, Illinois.
Comments: Safflower is grown primarily as an agricultural crop in the western half of the United States and other parts of the world. The flowerheads are a source of red and yellow dyes for clothing and food (now largely replaced by synthetic dyes), while vegetable oil is derived from its seeds. Safflower oil is high in oleic and linoleic fatty acids, and it is used as a source for cooking oil, salad oil, industrial oil, biodiesel fuel, margarine, soap, cosmetics, oil-based paints, and varnishes. Roasted or fried hulled seeds are edible to humans, while unhulled raw seeds are used as a source of food for birds. Young foliage and meal from processed seeds are edible to livestock (e.g., cattle & sheep). The primary advantage of Safflower over other agricultural crops is its ability to adapt to hot dry climates. Because of the spines on its foliage and floral bracts, Safflower resembles thistles (Cirsium spp., Carduus spp.), but the corollas of its flowerheads are yellow to red, rather than pink or purple. Unlike thistles, the achenes of Safflower lack tufts of hair at their apices, except for some uncommon cultivars that have achenes with short bristles. In addition, the widely spreading and spiny floral bracts of Safflower have a distinctive appearance.
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文章
Miss Chen
2018年07月30日
Description: This herbaceous plant is either a biennial or summer annual (usually the former). It consists initially of a rosette of basal leaves. These basal leaves are 4-12" long and 1¼-4" across; they are lanceolate-pinnatifid or elliptic-pinnatifid with occasional secondary lobes. The margins of these leaves have white to golden yellow spines; larger spines occur at the tips of the primary and secondary lobes, while smaller spines occur along their sides and sinuses. The upper surfaces of the basal leaves are medium green and glabrous, while their lower surfaces are light to medium green and mostly glabrous, except for some short pubescence along the midveins. The petioles of these basal leaves are short and broadly winged. Later, this plant bolts, becoming 1½-6' tall and either unbranched or branched. The lower stem (or stems) tends to be light green and nearly glabrous toward the bottom, becoming increasingly white-tomentose above (white hairs that are appressed and woolly). In addition, the stems are terete and relatively stout; they lack spines, except where extensions of the leaf margins are decurrent. Alternate leaves occur along these stems, becoming gradually smaller as they ascend; they are 2-6" long and ½-1½" across. Alternate leaves are narrowly pinnatifid-lanceolate or narrowly pinnatifid-elliptic in shape. Compared to the lobes of basal leaves, the lobes of alternate leaves are more shallow, although the tips of these latter lobes are still spined. Alternate leaves are sessile; their margins have decurrent extensions along the stems, where they are spiny. The upper stems terminate in individual flowerheads about 1-3" across on long erect peduncles (up to 2' long). These peduncles are terete, stout, and white-tomentose; they are largely naked, except for widely-spaced leafy bracts. The flowerheads often nod to one side. Each flowerhead has 100-1000 disk florets that are narrowly cylindrical below, while above they divide into linear lobes (5 lobes per floret). The corollas of these florets are pink to purplish pink (rarely white); the styles of these florets are strongly exerted. Around the base of each flowerhead, there are relatively large phyllaries in several series. These phyllaries are deltate-ovate in shape; outer phyllaries are ascending, widely spreading, or descending; sometimes they are also recurved. The tips of the phyllaries are stiff and spiny. Immature flowerheads have green phyllaries, but they later become purplish.
The blooming period occurs from early summer into the fall, lasting 1-4 months. The flowerheads are fragrant. Afterwards, the florets are replaced by achenes (4-5 mm. in length) with large tufts of hair. These achenes are bullet-shaped, slightly flattened, and ribbed. The primary hairs that are above these achenes have minute lateral hairs (may require 10x magnification to see). The achenes are distributed primarily by the wind. The root system develops a fleshy taproot.
Cultivation: The preference is full sun, mesic conditions, and calcareous soil that is derived from either limestone or sand. However, Nodding Thistle (Carduus nutans) will adapt to almost any soil that is not extremely acidic. The size of individual plants can vary considerably depending on soil fertility and moisture levels. This thistle can reseed itself aggressively and become invasive. The seeds can remain viable for 3 or more years.
Range & Habitat: The non-native Nodding Thistle (Carduus nutans) is occasional in most areas of Illinois (see Distribution Map), and it is probably still spreading within the state. This thistle is native to Eurasia and northern Africa; it was accidentally introduced into North America during the 19th century, possibly from dumped ship ballast along the east coast. In Illinois and other parts of North America, habitats include savannas, pastures, fallow fields, roadsides, areas along railroads, waste areas, and gardens or yards that use transported soil containing the seeds of this thistle. Nodding Thistle is particularly common in areas with calcareous sand (e.g., near major lakes) and limestone-derived soil. Disturbed areas are strongly preferred.
Faunal Associations: The flowerheads are cross-pollinated primarily by bumblebees and other long-tongued bees, butterflies, and skippers. In the absence of cross-pollination, the florets of the flowerheads are self-fertile. Both nectar and pollen are available as floral rewards. Because Nodding Thistle (Carduus nutans) is regarded as invasive in some parts of North America, various insects have been introduced from abroad to function as biocontrol agents. These species include: Rhinocyllus conicus (Thistlehead Weevil), whose larvae feed on the flowerheads; Trichosirocalus horridus (Thistle Crown Weevil), whose larvae feed on the growing points of rosettes and young shoots; Cheilosa corydon (Thistle Crown Fly), whose larvae burrow into shoots; Cassida rubiginosa (Thistle Tortoise Beetle), whose larvae and adults feed on leaves; and Psylliodes chalcomerus (Musk Thistle Leaf Beetle), whose larvae bore through stems, while the adults feed on leaves. Other insect feeders include Platyptilia carduidactylus (Artichoke Plume Moth) and Brachycaudus cardui (Thistle Aphid). The seeds of this thistle are eaten by a songbird, the Eastern Goldfinch, and the tufted hairs of its seeds are used in the construction of this bird's nests. Because of the spiny foliage, Nodding Thistle is rarely eaten by mammalian herbivores. However, sometimes cattle, sheep, and goats will eat the flowerheads or seedheads. It is unclear to what extent the seeds can survive passage in the digestive tracts of these animals, and thus their role in seed dispersal is still unclear.
Photographic Location: The photographed plant was cultivated in the webmaster's wildflower garden in Urbana, Illinois. However, this plant was found originally in the yard of the webmaster's apartment complex, where it had been transported in contaminated soil that was purchased from a local garden center.
Comments: Nodding Thistle (Carduus nutans) has very showy and fragrant flowerheads, while its foliage is quite spiny. Until the nodding flowerheads are produced, it can be difficult to distinguish from other thistles. Like the Eurasian Bull Thistle (Cirsium vulgare), Nodding Thistle can be distinguished from native thistles by the spines on its stems (as derived from the decurrent margins of its leaves). It can be distinguished from the Bull Thistle by differences in the shape, size, and color of their respective phyllaries (floral bracts). The phyllaries of Nodding Thistle are larger in size, more broad at their bases, and become purple-colored when the flowerheads bloom; the phyllaries of Bull Thistle remain green at this time. In addition, the flowerheads of Nodding Thistle are usually more broad than those of Bull Thistle. Thistle species in the Carduus genus differ from thistle species in the Cirsium genus by the structure of the tufted hairs above their seeds. The tufted hairs of Carduus spp. (Musk Thistles) have barbed hairs from minute lateral hairs, while the tufted hairs of Cirsium spp. (Thistles) are more plumose (feathery) from longer lateral hairs. This is why Carduus nutans is sometimes referred to as the 'Plumeless Thistle,' even though its seeds have tufts of hair.
The blooming period occurs from early summer into the fall, lasting 1-4 months. The flowerheads are fragrant. Afterwards, the florets are replaced by achenes (4-5 mm. in length) with large tufts of hair. These achenes are bullet-shaped, slightly flattened, and ribbed. The primary hairs that are above these achenes have minute lateral hairs (may require 10x magnification to see). The achenes are distributed primarily by the wind. The root system develops a fleshy taproot.
Cultivation: The preference is full sun, mesic conditions, and calcareous soil that is derived from either limestone or sand. However, Nodding Thistle (Carduus nutans) will adapt to almost any soil that is not extremely acidic. The size of individual plants can vary considerably depending on soil fertility and moisture levels. This thistle can reseed itself aggressively and become invasive. The seeds can remain viable for 3 or more years.
Range & Habitat: The non-native Nodding Thistle (Carduus nutans) is occasional in most areas of Illinois (see Distribution Map), and it is probably still spreading within the state. This thistle is native to Eurasia and northern Africa; it was accidentally introduced into North America during the 19th century, possibly from dumped ship ballast along the east coast. In Illinois and other parts of North America, habitats include savannas, pastures, fallow fields, roadsides, areas along railroads, waste areas, and gardens or yards that use transported soil containing the seeds of this thistle. Nodding Thistle is particularly common in areas with calcareous sand (e.g., near major lakes) and limestone-derived soil. Disturbed areas are strongly preferred.
Faunal Associations: The flowerheads are cross-pollinated primarily by bumblebees and other long-tongued bees, butterflies, and skippers. In the absence of cross-pollination, the florets of the flowerheads are self-fertile. Both nectar and pollen are available as floral rewards. Because Nodding Thistle (Carduus nutans) is regarded as invasive in some parts of North America, various insects have been introduced from abroad to function as biocontrol agents. These species include: Rhinocyllus conicus (Thistlehead Weevil), whose larvae feed on the flowerheads; Trichosirocalus horridus (Thistle Crown Weevil), whose larvae feed on the growing points of rosettes and young shoots; Cheilosa corydon (Thistle Crown Fly), whose larvae burrow into shoots; Cassida rubiginosa (Thistle Tortoise Beetle), whose larvae and adults feed on leaves; and Psylliodes chalcomerus (Musk Thistle Leaf Beetle), whose larvae bore through stems, while the adults feed on leaves. Other insect feeders include Platyptilia carduidactylus (Artichoke Plume Moth) and Brachycaudus cardui (Thistle Aphid). The seeds of this thistle are eaten by a songbird, the Eastern Goldfinch, and the tufted hairs of its seeds are used in the construction of this bird's nests. Because of the spiny foliage, Nodding Thistle is rarely eaten by mammalian herbivores. However, sometimes cattle, sheep, and goats will eat the flowerheads or seedheads. It is unclear to what extent the seeds can survive passage in the digestive tracts of these animals, and thus their role in seed dispersal is still unclear.
Photographic Location: The photographed plant was cultivated in the webmaster's wildflower garden in Urbana, Illinois. However, this plant was found originally in the yard of the webmaster's apartment complex, where it had been transported in contaminated soil that was purchased from a local garden center.
Comments: Nodding Thistle (Carduus nutans) has very showy and fragrant flowerheads, while its foliage is quite spiny. Until the nodding flowerheads are produced, it can be difficult to distinguish from other thistles. Like the Eurasian Bull Thistle (Cirsium vulgare), Nodding Thistle can be distinguished from native thistles by the spines on its stems (as derived from the decurrent margins of its leaves). It can be distinguished from the Bull Thistle by differences in the shape, size, and color of their respective phyllaries (floral bracts). The phyllaries of Nodding Thistle are larger in size, more broad at their bases, and become purple-colored when the flowerheads bloom; the phyllaries of Bull Thistle remain green at this time. In addition, the flowerheads of Nodding Thistle are usually more broad than those of Bull Thistle. Thistle species in the Carduus genus differ from thistle species in the Cirsium genus by the structure of the tufted hairs above their seeds. The tufted hairs of Carduus spp. (Musk Thistles) have barbed hairs from minute lateral hairs, while the tufted hairs of Cirsium spp. (Thistles) are more plumose (feathery) from longer lateral hairs. This is why Carduus nutans is sometimes referred to as the 'Plumeless Thistle,' even though its seeds have tufts of hair.
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Miss Chen
2018年07月24日
Description: This herbaceous perennial plant is 2-4' tall, branching abundantly in the upper half where the flowerheads occur. The stems are largely hairless, angular, and furrowed, although the upper flowering stems are usually pubescent. The lower stems often become reddish or woody in appearance with maturity. The alternate leaves are up to 4" long and 3" across, becoming smaller in size and more narrow as they ascend the stems. The upper surface of these leaves is green and hairless, while their lower surface is white from fine pubescent hairs. The lower and middle leaves usually have 1-2 pairs of deep primary lobes that are often irregularly spaced; these primary lobes are often shallowly cleft by one or more secondary lobes, or they have may a few large teeth. At the base of these leaves, there are often 1 or 2 small eared lobes. The upper leaves have few lobes or none, eventually becoming linear on the flowering stems.
The inflorescence is a large panicle of leafy spikes with flowerheads. Each flowerhead is 1/8" (3 mm.) across or a little larger, consisting of numerous rayless florets. The florets in the center of the flowerhead are fertile and perfect, while the florets along the outer margin of the flowerhead are fertile and pistillate. The central florets are tubular with 5 recurved lobes, while the marginal florets have only 1 or 2 lobes. All of these florets have a divided style. At the base of the flowerhead are several floral bracts that are finely pubescent. Except for their abundance, these flowerheads are inconspicuous. At the bud stage they are whitish green, becoming dull yellowish green or purplish green with maturity. The blooming period occurs from late summer to early fall, and lasts about 1 month. Pollination is by wind. Each floret is replaced by an oblong achene that is without a tuft of hairs. These achenes are small and light enough to be blown about by the wind. The root system is quite rhizomatous, and often produces clonal colonies of plants.
Cultivation: Mugwort prefers full or partial sun and moist to slightly dry conditions. It adapts well to loam, clay-loam, or gravelly soil, and slightly acid to alkaline conditions. This plant can spread aggressively, forming dense colonies that exclude other plants.
Range & Habitat: Surprisingly, Mugwort is a rather uncommon plant in Illinois, occurring in only a few counties in the northern half of the state (see Distribution Map). It was introduced into the United States from Eurasia as an herbal plant. Habitats include areas along railroads, edges of woods, prairie restorations, herbal gardens, and miscellaneous waste places. This plant usually occurs in disturbed areas, but it has displayed a capacity to invade more natural sites, even when fire is used as a management tool. This plant may become more of a problem in the future.
Faunal Associations: The flowerheads attract few insects because they are wind-pollinated. While the shrubby Artemisia spp. (Sagebrushes) of the western states are valuable to various kinds of wildlife, birds and mammals appear to make little use of the herbaceous Artemisia spp. that occur in the Midwest and NE states. The slightly aromatic foliage of Mugwort is bitter-tasting and toxic, containing cinerole and thujone. This latter substance is a neurotoxin. While Mugwort has been used in herbal medicine in the past, it can cause a variety of neurological problems and adverse reactions.
Photographic Location: Along the edge of a prairie restoration at Meadowbrook Park in Urbana, Illinois.
Comments: Mugwort is one of the introduced Artemisia spp. and rather nondescript in appearance. While significantly lobed, its leaves are usually broader than other Artemisia spp. and more tolerant of shade. These leaves are bicolored: green and largely hairless on the upper surface, but finely pubescent and powdery white underneath, whereas other Artemisia spp. tend to be either hairy or glabrous on both sides and less bicolored. Some Artemisia spp. have hairy or pubescent stems, while the stems of Mugwort are largely hairless (except for the upper flowering stems). Mugwort is unusual in having recurved lobes on its central disk florets – other Artemisia spp. usually have erect or spreading lobes on their disk florets. Because these florets are quite small in size, this can be difficult to observe without magnification from a hand or eye lens.
The inflorescence is a large panicle of leafy spikes with flowerheads. Each flowerhead is 1/8" (3 mm.) across or a little larger, consisting of numerous rayless florets. The florets in the center of the flowerhead are fertile and perfect, while the florets along the outer margin of the flowerhead are fertile and pistillate. The central florets are tubular with 5 recurved lobes, while the marginal florets have only 1 or 2 lobes. All of these florets have a divided style. At the base of the flowerhead are several floral bracts that are finely pubescent. Except for their abundance, these flowerheads are inconspicuous. At the bud stage they are whitish green, becoming dull yellowish green or purplish green with maturity. The blooming period occurs from late summer to early fall, and lasts about 1 month. Pollination is by wind. Each floret is replaced by an oblong achene that is without a tuft of hairs. These achenes are small and light enough to be blown about by the wind. The root system is quite rhizomatous, and often produces clonal colonies of plants.
Cultivation: Mugwort prefers full or partial sun and moist to slightly dry conditions. It adapts well to loam, clay-loam, or gravelly soil, and slightly acid to alkaline conditions. This plant can spread aggressively, forming dense colonies that exclude other plants.
Range & Habitat: Surprisingly, Mugwort is a rather uncommon plant in Illinois, occurring in only a few counties in the northern half of the state (see Distribution Map). It was introduced into the United States from Eurasia as an herbal plant. Habitats include areas along railroads, edges of woods, prairie restorations, herbal gardens, and miscellaneous waste places. This plant usually occurs in disturbed areas, but it has displayed a capacity to invade more natural sites, even when fire is used as a management tool. This plant may become more of a problem in the future.
Faunal Associations: The flowerheads attract few insects because they are wind-pollinated. While the shrubby Artemisia spp. (Sagebrushes) of the western states are valuable to various kinds of wildlife, birds and mammals appear to make little use of the herbaceous Artemisia spp. that occur in the Midwest and NE states. The slightly aromatic foliage of Mugwort is bitter-tasting and toxic, containing cinerole and thujone. This latter substance is a neurotoxin. While Mugwort has been used in herbal medicine in the past, it can cause a variety of neurological problems and adverse reactions.
Photographic Location: Along the edge of a prairie restoration at Meadowbrook Park in Urbana, Illinois.
Comments: Mugwort is one of the introduced Artemisia spp. and rather nondescript in appearance. While significantly lobed, its leaves are usually broader than other Artemisia spp. and more tolerant of shade. These leaves are bicolored: green and largely hairless on the upper surface, but finely pubescent and powdery white underneath, whereas other Artemisia spp. tend to be either hairy or glabrous on both sides and less bicolored. Some Artemisia spp. have hairy or pubescent stems, while the stems of Mugwort are largely hairless (except for the upper flowering stems). Mugwort is unusual in having recurved lobes on its central disk florets – other Artemisia spp. usually have erect or spreading lobes on their disk florets. Because these florets are quite small in size, this can be difficult to observe without magnification from a hand or eye lens.
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Miss Chen
2018年07月22日
Asparagus (Asparagus officinalis) spears are the new shoots of asparagus plants that grow in spring. Asparagus grows from seed, and plants live 20 to 30 years in good growing conditions. In U.S. Department of Agriculture plant hardiness zones 4 through 8, asparagus is hardy, and plants grow 3 to 5 feet tall. Young asparagus shoots can sometimes cause skin irritation, and the red berries produced by female asparagus plants are poisonous.
Asparagus Roots
Asparagus root systems are called crowns. Asparagus growers start plants from seed and sell asparagus crowns that are one or two years old. Each crown has a central bud, and thick roots spreading out sideways. Shoots grow from the central bud.
Asparagus roots grow horizontally, not vertically. Over time, they form a wide, tuberous mat. When growing asparagus, it's important to select a growing area that can be left undisturbed for years. After planting, asparagus roots should not be moved.
Asparagus Plants
Asparagus plants develop many branched stems, which die down at the end of the growing season. Shoots develop daily on asparagus plants in spring. Newly planted crowns can produce shoots five or six weeks after planting. After a crop of young shoots is harvested, later shoots are allowed to develop so the plants can store energy for next year's crop.
As shoots grow, they produce many stems, which branch off into smaller stems. Rings of thin, hairlike structures appear on the smaller stems, which give mature asparagus plants a feathery appearance. True asparagus leaves are scalelike and tiny, and they can be seen most easily on new shoots. Asparagus stems turn yellow and wither in fall, often after the first frost.
Female and Male Asparagus
Asparagus plants are female or male. Female plants produce more stems than male plants, but the stems are thinner. Female asparagus plants also produce bright red summer berries, which contain the plant's seeds. Seeds from fallen berries can create problems the following year, when the asparagus bed becomes overrun with asparagus seedlings.
Newer varieties of asparagus are mostly male or all male plants. Male plants put all their energy into shoot production and don't waste energy on producing fruit. They also don't create problems with asparagus seedlings.
New Varieties
New asparagus varieties offer disease resistance and a range of colors. Asparagus "Jersey Knight" (Asparagus officinalis "Jersey Knight") is resistant to rust, fusarium wilt, and root and crown rot. Asparagus "Purple Passion" (Asparagus "Purple Passion") features purple spears, though these turn green when cooked. "Jersey Knight" and "Purple Passion" are hardy in USDA zones 3 through 10.
Asparagus "Jersey Giant" (Asparagus officinalis "Jersey Giant"), which is hardy in USDA zones 4 through 7, produces green spears with purple bracts. Bracts are leaflike structures. "Jersey Giant" produces two to three times more spears than some older varieties.
Asparagus Roots
Asparagus root systems are called crowns. Asparagus growers start plants from seed and sell asparagus crowns that are one or two years old. Each crown has a central bud, and thick roots spreading out sideways. Shoots grow from the central bud.
Asparagus roots grow horizontally, not vertically. Over time, they form a wide, tuberous mat. When growing asparagus, it's important to select a growing area that can be left undisturbed for years. After planting, asparagus roots should not be moved.
Asparagus Plants
Asparagus plants develop many branched stems, which die down at the end of the growing season. Shoots develop daily on asparagus plants in spring. Newly planted crowns can produce shoots five or six weeks after planting. After a crop of young shoots is harvested, later shoots are allowed to develop so the plants can store energy for next year's crop.
As shoots grow, they produce many stems, which branch off into smaller stems. Rings of thin, hairlike structures appear on the smaller stems, which give mature asparagus plants a feathery appearance. True asparagus leaves are scalelike and tiny, and they can be seen most easily on new shoots. Asparagus stems turn yellow and wither in fall, often after the first frost.
Female and Male Asparagus
Asparagus plants are female or male. Female plants produce more stems than male plants, but the stems are thinner. Female asparagus plants also produce bright red summer berries, which contain the plant's seeds. Seeds from fallen berries can create problems the following year, when the asparagus bed becomes overrun with asparagus seedlings.
Newer varieties of asparagus are mostly male or all male plants. Male plants put all their energy into shoot production and don't waste energy on producing fruit. They also don't create problems with asparagus seedlings.
New Varieties
New asparagus varieties offer disease resistance and a range of colors. Asparagus "Jersey Knight" (Asparagus officinalis "Jersey Knight") is resistant to rust, fusarium wilt, and root and crown rot. Asparagus "Purple Passion" (Asparagus "Purple Passion") features purple spears, though these turn green when cooked. "Jersey Knight" and "Purple Passion" are hardy in USDA zones 3 through 10.
Asparagus "Jersey Giant" (Asparagus officinalis "Jersey Giant"), which is hardy in USDA zones 4 through 7, produces green spears with purple bracts. Bracts are leaflike structures. "Jersey Giant" produces two to three times more spears than some older varieties.
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Miss Chen
2018年07月16日
Fast-growing annual vines with yellow blooms up to 5 inches across, loofah plants (Luffa spp.) usually require a four-month growing season to produce mature gourds. Therefore, gardeners in the north may need to start them indoors about 4 to 6 weeks before the last spring frost. During the summer and early autumn, the heavy vines should be grown in humus-rich soil in full sun, preferably on a sturdy trellis or fence to keep their 1 to 2-foot gourds off the ground. Those fruits must be harvested before or just after the first autumn frost and are used both as bath sponges and dish scrubbers.
Pick and Peel Mature Sponges
If you live in an area with a long growing season, Jack Arnott of Cobb County Extension Service recommends that you allow your loofah gourds to dry on the vine until their skin is brown and brittle and you hear seeds rattle when you shake those gourds. Break open the skin at the blossom the end opposite the stem of the gourd to reach those seeds, if you wish to save them. It usually is easy to pick off the rest of the brittle skin with your fingers to reveal the sponge beneath. If you prefer, you can dunk the gourds in a bucket of water instead -- for any time period lasting from 5 minutes to several days -- and peel off their skins in wet strips.
Pick and Peel Immature Sponges
If your growing season isn't quite long enough, Jeanine Davis of North Carolina State University Cooperative Extension reports that you can harvest adequate sponges from gourds which have only partially yellowed, as long as their skins are beginning to slip. After you make an opening to save the seeds, grab the end of one of the fibers running the length of the gourd's ridges and pull on it to unzip the remaining skin.
Clean and Dry Sponges
Immediately plunge a less-than-mature sponge into a bucket of water to wash out any juices that remain due to its only half-dry condition. Although the sponge still will be white at that stage, it's a good idea to soak it in a bleach solution to eliminate fungi and bacteria. Mature sponges also should be immersed in bleach solution, of 4 tablespoons of bleach per 1 gallon of water, both to kill contaminants and to brighten their naturally off-white color.
After disinfecting the sponges, rinse them with clean water and spread them in the sun to dry. A porous surface works well for this purpose. You can turn screens into drying tables by laying them horizontally on top of sawhorses.
Pick and Peel Mature Sponges
If you live in an area with a long growing season, Jack Arnott of Cobb County Extension Service recommends that you allow your loofah gourds to dry on the vine until their skin is brown and brittle and you hear seeds rattle when you shake those gourds. Break open the skin at the blossom the end opposite the stem of the gourd to reach those seeds, if you wish to save them. It usually is easy to pick off the rest of the brittle skin with your fingers to reveal the sponge beneath. If you prefer, you can dunk the gourds in a bucket of water instead -- for any time period lasting from 5 minutes to several days -- and peel off their skins in wet strips.
Pick and Peel Immature Sponges
If your growing season isn't quite long enough, Jeanine Davis of North Carolina State University Cooperative Extension reports that you can harvest adequate sponges from gourds which have only partially yellowed, as long as their skins are beginning to slip. After you make an opening to save the seeds, grab the end of one of the fibers running the length of the gourd's ridges and pull on it to unzip the remaining skin.
Clean and Dry Sponges
Immediately plunge a less-than-mature sponge into a bucket of water to wash out any juices that remain due to its only half-dry condition. Although the sponge still will be white at that stage, it's a good idea to soak it in a bleach solution to eliminate fungi and bacteria. Mature sponges also should be immersed in bleach solution, of 4 tablespoons of bleach per 1 gallon of water, both to kill contaminants and to brighten their naturally off-white color.
After disinfecting the sponges, rinse them with clean water and spread them in the sun to dry. A porous surface works well for this purpose. You can turn screens into drying tables by laying them horizontally on top of sawhorses.
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Miss Chen
2018年07月11日
Description: This herbaceous perennial plant forms both basal leaves and erect to ascending stems with alternate leaves; the latter are 2-4' tall, branching occasionally. The stems are grayish green to nearly white, densely canescent, and terete, becoming more glabrous and slightly woody with age. Both the basal and lower alternate leaves are 2–4½" long and ¾–1¾" across (excluding their petioles); they are bipinnatifid to tripinnatifid. These leaves are deeply divided into primary lobes, while their ultimate lobes are more shallow and cleft. The ultimate lobes are 2-4 mm. across and narrowly oblong to narrowly oblanceolate in shape, tapering abruptly into bluntly acute tips. The middle alternate leaves are less divided and slightly smaller in size, while the upper alternate leaves are simple or sparingly lobed and even smaller in size. Both the upper and lower sides of the leaves are grayish green and sparsely to moderately canescent. The basal and lower alternate leaves have long petioles, while the middle alternate leaves have shorter petioles, and the upper alternate leaves are sessile or nearly so. Like the leaves, the petioles are grayish green and canescent. The foliage of this plant has a sage-like aroma with slightly bitter overtones. The upper stems terminate in panicles of flowers. Along the primary rachises of these panicles, there are primary leafy bracts at the bases of the secondary rachises; these primary bracts are up to 1" long, linear-oblong in shape, grayish green to nearly white, and canescent.
Secondary leafy bracts also occur at the bases of the peduncles on the secondary rachises; these secondary bracts are similar to the primary leafy bracts, except they are smaller in size. Both the primary and secondary rachises of the panicles are grayish green to nearly white and moderately to densely canescent; they are flat or slightly concave along their upper sides and rounded along their lower sides. The nodding flowerheads are 3-5 mm. across and 2-3 mm. tall; they are subgloboid in shape. Each flowerhead has 20-40 perfect disk florets that are surrounded by 10-20 pistillate disk florets; both types of florets are fertile. The florets are seperated by abundant silky hairs that originate from the receptacle. The tiny corollas of these florets are tubular in shape and 5-lobed along their upper rims. Overall, the appearance of these florets is yellowish brown. Along the sides of each flowerhead, there are small appressed phyllaries (floral bracts) in several overlapping series; these floral bracts are whitish green, densely canescent, and oblong to ovate in shape. The flowerheads have short curved peduncles that are whitish green and densely canescent. The blooming period occurs from mid-summer to early autumn, lasting 2-3 weeks for a colony of plants. The florets are cross-pollinated by the wind. Afterwards, the florets are replaced by small achenes. Mature achenes are 0.5–1 mm. long, narrowly oblongoid-oblanceoloid in shape, and light brown; they lack tufts of hair. The root system consists of a taproot up to ½" across. This plant reproduces by reseeding itself.
Cultivation: The preference is full or partial sun, moist to dry-mesic conditions, and soil containing loam, clay-loam, or some gravel. The soil should be well-drained. The size of individual plants can be highly variable depending on their age, moisture conditions, and soil fertility. For a herbaceous wormwood species (Artemisia), Absinthe tends to be long-lived.
Range & Habitat: Naturalized populations of Absinthe can be found in NE Illinois and scattered counties elsewhere, where it is relatively rare (see Distribution Map). All of these naturalized plants have escaped from cultivation. Absinthe was introduced into North America from Europe as an ornamental and medicinal plant. It is still cultivated occasionally in herb gardens today. In North America, this plant is more common in the northern plains of the United States and south-central Canada, where it is regarded as a weed of pastures. Habitats include pastures, sunny fence rows, gravelly areas along railroads, old homestead sites, and waste areas. Habitats with a history of disturbance are strongly preferred. In Illinois, Absinthe has difficulty to competing with taller native plants in natural areas.
Faunal Associations: Several species of aphids are known to feed on Absinthe (Artemisia absinthium); many of these species originated from Europe. Examples include such species as Coloradoa absinthii, Coloradoa angelicae, Coloradoa artemisiae, Macrosiphoniella absinthii (Absinthe Aphid), and other Macrosiphoniella spp. (Blackman & Eastop, 2013; Robinson & Bradley, 1965). Other insects that feed on wormwood species (Artemisia spp.) include Aphis middletonii(Erigeron Root Aphid), larvae of the leaf-miner fly Calycomyza artemisiae (Wormseed Webworm), larvae of the Gelechiid moth, Scrobipalpula artemisiella (Wormseed Webworm), and larvae of the Tortricid moths Eucosma agricolana and Phaneta dorsiatomana (Hottes & Frison, 1931; Spencer & Steyskal, 1986; Marcovitch, 1916; Miller, 1987). Some grasshoppers feed on these plants as well, including Hesperotettix viridis (Meadow Purple-striped Grasshopper), Hypochloa alba (Cudweed Grasshopper), and Melanoplus angustipennis (Narrow-winged Sand Grasshopper); see Vickery & Kevan (1985). Because the foliage of Absinthe is aromatic and bitter, it is not preferred as a source of food by herbivorous mammals. However, cattle and other domesticated livestock will feed on the foliage of Absinthe if little else is available. The consumption of a large quantity of foliage is potentially harmful as it contains the neurotoxin, thujone.
Photographic Location: An herb garden at Meadowbrook Park in Urbana, Illinois.
Comments: Absinthe (Artemisia absinthium) has been used to flavor an alcoholic liquor by the same name. Excessive consumption of this liquor has the potential to cause toxic effects and its use in some countries has been banned. Absinthe is similar in appearance to several other wormseed species (Artemisia spp.); both native and non-native species are present in Illinois. A native species that occurs in sandy areas, Beach Wormwood (Artemisia campestris), can be distinguished by the longer length and narrowness of the lobes of its leaves, the sterile florets in the center of its flowerheads, and the lack of villous hairs on the receptacle of its flowerheads. The presence of the last characteristic (villous hairs on the receptacles of the flowerheads) distinguishes Absinthe from all other wormseed species in Illinois, except for Prairie Sagebrush (Artemisia frigida). Prairie Sagebrush has smaller leaves with more narrow lobes (1 mm. across or less) than Absinthe, while its flowerheads are slightly larger in size (5-6 mm. across and 3-5 mm. tall). It is primarily a western species that is rarely found in Illinois.
Secondary leafy bracts also occur at the bases of the peduncles on the secondary rachises; these secondary bracts are similar to the primary leafy bracts, except they are smaller in size. Both the primary and secondary rachises of the panicles are grayish green to nearly white and moderately to densely canescent; they are flat or slightly concave along their upper sides and rounded along their lower sides. The nodding flowerheads are 3-5 mm. across and 2-3 mm. tall; they are subgloboid in shape. Each flowerhead has 20-40 perfect disk florets that are surrounded by 10-20 pistillate disk florets; both types of florets are fertile. The florets are seperated by abundant silky hairs that originate from the receptacle. The tiny corollas of these florets are tubular in shape and 5-lobed along their upper rims. Overall, the appearance of these florets is yellowish brown. Along the sides of each flowerhead, there are small appressed phyllaries (floral bracts) in several overlapping series; these floral bracts are whitish green, densely canescent, and oblong to ovate in shape. The flowerheads have short curved peduncles that are whitish green and densely canescent. The blooming period occurs from mid-summer to early autumn, lasting 2-3 weeks for a colony of plants. The florets are cross-pollinated by the wind. Afterwards, the florets are replaced by small achenes. Mature achenes are 0.5–1 mm. long, narrowly oblongoid-oblanceoloid in shape, and light brown; they lack tufts of hair. The root system consists of a taproot up to ½" across. This plant reproduces by reseeding itself.
Cultivation: The preference is full or partial sun, moist to dry-mesic conditions, and soil containing loam, clay-loam, or some gravel. The soil should be well-drained. The size of individual plants can be highly variable depending on their age, moisture conditions, and soil fertility. For a herbaceous wormwood species (Artemisia), Absinthe tends to be long-lived.
Range & Habitat: Naturalized populations of Absinthe can be found in NE Illinois and scattered counties elsewhere, where it is relatively rare (see Distribution Map). All of these naturalized plants have escaped from cultivation. Absinthe was introduced into North America from Europe as an ornamental and medicinal plant. It is still cultivated occasionally in herb gardens today. In North America, this plant is more common in the northern plains of the United States and south-central Canada, where it is regarded as a weed of pastures. Habitats include pastures, sunny fence rows, gravelly areas along railroads, old homestead sites, and waste areas. Habitats with a history of disturbance are strongly preferred. In Illinois, Absinthe has difficulty to competing with taller native plants in natural areas.
Faunal Associations: Several species of aphids are known to feed on Absinthe (Artemisia absinthium); many of these species originated from Europe. Examples include such species as Coloradoa absinthii, Coloradoa angelicae, Coloradoa artemisiae, Macrosiphoniella absinthii (Absinthe Aphid), and other Macrosiphoniella spp. (Blackman & Eastop, 2013; Robinson & Bradley, 1965). Other insects that feed on wormwood species (Artemisia spp.) include Aphis middletonii(Erigeron Root Aphid), larvae of the leaf-miner fly Calycomyza artemisiae (Wormseed Webworm), larvae of the Gelechiid moth, Scrobipalpula artemisiella (Wormseed Webworm), and larvae of the Tortricid moths Eucosma agricolana and Phaneta dorsiatomana (Hottes & Frison, 1931; Spencer & Steyskal, 1986; Marcovitch, 1916; Miller, 1987). Some grasshoppers feed on these plants as well, including Hesperotettix viridis (Meadow Purple-striped Grasshopper), Hypochloa alba (Cudweed Grasshopper), and Melanoplus angustipennis (Narrow-winged Sand Grasshopper); see Vickery & Kevan (1985). Because the foliage of Absinthe is aromatic and bitter, it is not preferred as a source of food by herbivorous mammals. However, cattle and other domesticated livestock will feed on the foliage of Absinthe if little else is available. The consumption of a large quantity of foliage is potentially harmful as it contains the neurotoxin, thujone.
Photographic Location: An herb garden at Meadowbrook Park in Urbana, Illinois.
Comments: Absinthe (Artemisia absinthium) has been used to flavor an alcoholic liquor by the same name. Excessive consumption of this liquor has the potential to cause toxic effects and its use in some countries has been banned. Absinthe is similar in appearance to several other wormseed species (Artemisia spp.); both native and non-native species are present in Illinois. A native species that occurs in sandy areas, Beach Wormwood (Artemisia campestris), can be distinguished by the longer length and narrowness of the lobes of its leaves, the sterile florets in the center of its flowerheads, and the lack of villous hairs on the receptacle of its flowerheads. The presence of the last characteristic (villous hairs on the receptacles of the flowerheads) distinguishes Absinthe from all other wormseed species in Illinois, except for Prairie Sagebrush (Artemisia frigida). Prairie Sagebrush has smaller leaves with more narrow lobes (1 mm. across or less) than Absinthe, while its flowerheads are slightly larger in size (5-6 mm. across and 3-5 mm. tall). It is primarily a western species that is rarely found in Illinois.
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Miss Chen
2018年07月11日
Description: This perennial wildflower develops a rosette of basal leaves, from which there develops one or more flowering stalks about 1¾-4' tall. The blades of the basal leaves are ½-2' long and 1½-6" across; they are broadly oblong-elliptic in shape and finely crenate-serrate along their margins. The petioles of the basal leaves are often as long as the blades. The basal leaves are widely spreading and rather floppy; their margins often undulate up-and-down. The stems of Horseradish are light to medium green and glabrous. Alternate leaves become smaller in size as they ascend these stems; their blades are 1-6" long and ¼-2" across. The blades of alternate leaves are narrowly elliptic to broadly oblong-lanceolate in shape and their margins are coarsely crenate-serrate to shallowly pinnatifid; they are sessile or with short petioles. The upper blade surfaces of both basal and alternate leaves are medium to dark green and glabrous, while their lower surfaces are a more pale shade of green and glabrous below.
The central stem and upper axillary stems terminate in either racemes or panicles of flowers about 4-16" in length. The flowers bloom toward the apex of each raceme (or branch of a panicle), while seedpods develop below. Each flower spans about 1/3" (8 mm.) across, consisting of 4 white petals, 4 light green sepals, 6 stamens, and a pistil with a short style. The petals are about twice the length of the sepals. The ascending pedicels are ¼-¾" in length, light green, and glabrous, becoming longer as the seedpods develop. The central stalks and branches of the racemes and panicles are light green and glabrous. The blooming period can occur from mid-spring to mid-summer and lasts about 2 months. The flowers are replaced by cylindrical seedpods up to ¼" (6 mm.) long; each seedpod can contain up to 8 seeds. The root system consists of a stout taproot and stout rhizomes. Clonal colonies of plants are often produced.
Cultivation: The preference is full or partial sun, moist conditions, and fertile soil containing loam or silt-loam. Because of its underground rhizomes, Horseradish can spread aggressively.
Range & Habitat: The non-native Horseradish is occasional in most areas of Illinois, except in the SE section of the state, where it is rare or absent (see Distribution Map). This plant was introduced into North America from Europe during colonial times; it is native to SE Europe and parts of SW Asia. Habitats include streambanks, ditches, fence rows, low areas along roads and railroads, abandoned fields, vacant lots, disturbed open woodlands, and waste areas. Horseradish is still cultivated in gardens as a culinary herb. It is usually found in disturbed areas.
Faunal Associations: The nectar and pollen of the flowers attract small bees, flies, small butterflies, and probably other insects. Several leaf beetles (Chrysomelidae) have been observed to feed on Horseradish, specifically: Entomoscelis americana, Phaedon laevigatus, Phyllotreta armoraciae (Horseradish Flea Beetle), Phyllotreta bipustulata, Phyllotreta conjuncta, Phyllotreta cruciferae, Phyllotreta oblonga, Phyllotreta punctulata, Phyllotreta striolata, and Phyllotreta zimmermanni (see Clark et al., 2004). These species are mostly flea beetles (a subfamily of leaf beetles) that feed on the foliage and sometimes the roots. Other insect feeders include Murgantia histrionica (Harlequin Bug), the caterpillars of Lascoria ambigualis (Ambiguous Moth), and the caterpillars of Pieris rapae (Cabbage White). Because of high levels of mustard oil from the conversion of glucosinolates, Horseradish can produce toxic effects on mammalian herbivores, especially the pungent roots.
Photographic Location: A roadside ditch in NW Ohio, and the Toledo Botanical Garden in Toledo, Ohio.
Comments: In the United States, the thick roots of Horseradish are grated to flavor various sauces for food (primarily dishes of beef, pork, and seafood). Such sauces usually contain vinegar, mayonnaise, or pureed tomatoes. Because of the warm climate during summer and the long growing-season, Horseradish usually produces both seedpods and viable seeds in Illinois and other areas of the lower Midwest. Apparently this rarely happens in Great Britain and other areas of Europe where the climate is cool and the growing-season is too short. However, Horseradish is readily propagated by dividing its roots. Because of the size and abundance of its flowers, Horseradish is fairly showy while it is in bloom, especially for a species in the Mustard family. It is also larger in size than most species in this plant family. Horseradish can be distinguished from similar species by the size of its white flowers (about 1/3" or 8 mm. across), the appearance of its basal and alternate leaves, its small cylindrical seedpods, and the pungent odor of its roots. Because the classification of Horseradish has been unstable in the past, it is sometimes referred to as Armoracia lapathifolia, Cochlearia armoracia, and Rorippa armoracia.
The central stem and upper axillary stems terminate in either racemes or panicles of flowers about 4-16" in length. The flowers bloom toward the apex of each raceme (or branch of a panicle), while seedpods develop below. Each flower spans about 1/3" (8 mm.) across, consisting of 4 white petals, 4 light green sepals, 6 stamens, and a pistil with a short style. The petals are about twice the length of the sepals. The ascending pedicels are ¼-¾" in length, light green, and glabrous, becoming longer as the seedpods develop. The central stalks and branches of the racemes and panicles are light green and glabrous. The blooming period can occur from mid-spring to mid-summer and lasts about 2 months. The flowers are replaced by cylindrical seedpods up to ¼" (6 mm.) long; each seedpod can contain up to 8 seeds. The root system consists of a stout taproot and stout rhizomes. Clonal colonies of plants are often produced.
Cultivation: The preference is full or partial sun, moist conditions, and fertile soil containing loam or silt-loam. Because of its underground rhizomes, Horseradish can spread aggressively.
Range & Habitat: The non-native Horseradish is occasional in most areas of Illinois, except in the SE section of the state, where it is rare or absent (see Distribution Map). This plant was introduced into North America from Europe during colonial times; it is native to SE Europe and parts of SW Asia. Habitats include streambanks, ditches, fence rows, low areas along roads and railroads, abandoned fields, vacant lots, disturbed open woodlands, and waste areas. Horseradish is still cultivated in gardens as a culinary herb. It is usually found in disturbed areas.
Faunal Associations: The nectar and pollen of the flowers attract small bees, flies, small butterflies, and probably other insects. Several leaf beetles (Chrysomelidae) have been observed to feed on Horseradish, specifically: Entomoscelis americana, Phaedon laevigatus, Phyllotreta armoraciae (Horseradish Flea Beetle), Phyllotreta bipustulata, Phyllotreta conjuncta, Phyllotreta cruciferae, Phyllotreta oblonga, Phyllotreta punctulata, Phyllotreta striolata, and Phyllotreta zimmermanni (see Clark et al., 2004). These species are mostly flea beetles (a subfamily of leaf beetles) that feed on the foliage and sometimes the roots. Other insect feeders include Murgantia histrionica (Harlequin Bug), the caterpillars of Lascoria ambigualis (Ambiguous Moth), and the caterpillars of Pieris rapae (Cabbage White). Because of high levels of mustard oil from the conversion of glucosinolates, Horseradish can produce toxic effects on mammalian herbivores, especially the pungent roots.
Photographic Location: A roadside ditch in NW Ohio, and the Toledo Botanical Garden in Toledo, Ohio.
Comments: In the United States, the thick roots of Horseradish are grated to flavor various sauces for food (primarily dishes of beef, pork, and seafood). Such sauces usually contain vinegar, mayonnaise, or pureed tomatoes. Because of the warm climate during summer and the long growing-season, Horseradish usually produces both seedpods and viable seeds in Illinois and other areas of the lower Midwest. Apparently this rarely happens in Great Britain and other areas of Europe where the climate is cool and the growing-season is too short. However, Horseradish is readily propagated by dividing its roots. Because of the size and abundance of its flowers, Horseradish is fairly showy while it is in bloom, especially for a species in the Mustard family. It is also larger in size than most species in this plant family. Horseradish can be distinguished from similar species by the size of its white flowers (about 1/3" or 8 mm. across), the appearance of its basal and alternate leaves, its small cylindrical seedpods, and the pungent odor of its roots. Because the classification of Horseradish has been unstable in the past, it is sometimes referred to as Armoracia lapathifolia, Cochlearia armoracia, and Rorippa armoracia.
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Miss Chen
2018年07月10日
Description: This herbaceous plant is a winter or spring annual, producing leafy and flowering stems about 4-18" (10-45 cm.) long. These stems branch primarily near the base of the plant and they are ascending to widely sprawling. Individual stems are whitish green to light reddish green, terete, and woolly-pubescent. Alternate leaves occur along these stems that are ¾-2" (2-5 cm.) long and about one-half as much across; they are broadly oblong in outline, while their structure is deeply bipinnatifid. The ultimate leaf segments are 1.5-5.0 mm. long and about one-third as much across; these segments are oblong-acute in shape. The leaves are pale green and they are covered with short woolly pubescence that becomes more sparse with age. The short petioles are relatively broad, flattened, and whitish green to nearly white; they usually have simple or pinnate lobes along their margins that resemble the leaf segments.
The upper stems terminate in individual flowerheads that span about ¾-1¼" (2-3 cm.) across; these flowerheads have peduncles that are 1½-6" (4-15 cm.) in length. These peduncles are pale green, terete, and woolly-pubescent. Usually, small alternate bracts occur along the peduncles that resemble the leaves. Each daisy-like flowerhead has 10-18 ray florets that surround numerous disk florets; the ray florets are fertile and pistillate, while the disk florets are fertile and perfect. The petaloid rays of the ray florets are white, oblong in shape, and notched at their tips. The tiny corollas of the disk florets are yellow, tubular in shape, and 5-lobed at their apices; these lobes are triangular in shape. Alongside the disk florets, there are chaffy scales about 4 mm. in length. These scales are oblanceolate in shape and their tips are acute; sometimes these tips are awn-like. At the base of each flowerhead, there are 1-2 series of phyllaries (floral bracts) that are broadly oblong in shape. Individual phyllaries have convex central ridges that are light green, wide membranous margins that are white to light brown, and woolly pubescence; the phyllaries become chaffy with age. The foliage of this plant lacks a significant fragrance, although the crushed flowerheads are mildly fragrant (resembling apple-pineapple). The flowerheads are solid, lacking hollow centers. The blooming period usually occurs from late spring to mid-summer, lasting about 1-2 months, although some plants may bloom later in the year.
At maturity, the seedheads are ovoid in shape. The achenes are 1.5-2.5 mm. in length, oblanceoloid in shape, and slightly 4-angled; they are truncate at their apices, where they lack tufts of hair or significant scales. The sides of mature achenes have longitudinal ribs that are readily visible. The achenes are distributed to a limited extent by wind and probably by water at some locations. The root system consists of a shallow much-branched taproot or it is fibrous. Reproduction is by seeds.
Cultivation: The preference is full sun, moist to dry-mesic conditions, and a calcareous soil containing clay-loam, loam, silt, gravel, or sand. Drought tolerance is good. The seeds can remain viable in the ground for 10 years or more (Kay, 1971).
Range & Habitat: Field Chamomile has been found in scattered locations across Illinois (see Distribution Map), but this non-native plant is relatively uncommon within the state. It was introduced into North America from Eurasia, where it is native. In Illinois, habitats consist of fallow fields, roadsides, flood zones along drainage canals and retention ponds, vacant lots and abandoned homestead sites, and waste areas. Highly disturbed areas are preferred.
Faunal Associations: The flowerheads probably attract small bees, various flies (including Syrphid flies), and other insects. Both nectar and pollen are available as floral rewards to such visitors. Insects that feed destructively on Field Chamomile and other Anthemis spp. include Polymerus basalis (Red-Spotted Aster Mirid) and two aphids, Macrosiphoniella tanacetaria and Macrosiphoniella tapuskae. The former aphid is typically found on the flowerheads, peduncles, and upper stems, while the latter aphid is typically found on the lower leaves. The polyphagous caterpillars of a moth, Orthonama obstipata (The Gem), have been reported to feed on mayweeds by Covell (1984/2005). Field Chamomile belongs to the group of plants that are commonly referred to as mayweeds in Europe. The foliage of Field Chamomile is probably browsed sparingly by mammalian herbivores, while Canada Geese seem to avoid it. Because the seeds can pass through the gastrointestinal tracts of both cattle and pigeons and remain viable (Kay, 1971), these animals may spread them to new areas. It is also possible for the seeds to cling to the bottoms of the muddy shoes of people and the muddy hoofs of animals, by which means they can spread to new areas.
Photographic Location: Along a drainage canal and retention pond area in Champaign, Illinois.
Comments: Field Chamomile (Anthemis arvensis) is one of the plants that are commonly referred to as mayweeds. Examples of these species include Anthemis cotula (Dog Fennel), Chamaemelum nobile (Roman Chamomile), Matricaria recutita (German Chamomile), and Tripleurospermum perforatum (Scentless Chamomile). As a group, they are difficult to distinguish from each other. All of these species have daisy-like flowerheads that resemble those of Leucanthemum vulgare (Ox-Eye Daisy), but their foliage is deeply dissected (typically bipinnatifid). Field Chamomile can be distinguished from other mayweeds by its flat leaf-segments (rather than terete leaf-segments), by the presence and shape of the chaffy scales in its flowerheads, by the woolly pubescence of its foliage, and by the appearance of its achenes. The foliage of Field Chamomile lacks the pleasant fragrance of Roman Chamomile, nor does it possess the unpleasant odor of Dog Fennel. Similar to German Chamomile, the crushed flowerheads of Field Chamomile are mildly fragrant, but it has completely solid flowerheads, whereas the flowerheads of German Chamomile have interiors that are partly hollow.
The upper stems terminate in individual flowerheads that span about ¾-1¼" (2-3 cm.) across; these flowerheads have peduncles that are 1½-6" (4-15 cm.) in length. These peduncles are pale green, terete, and woolly-pubescent. Usually, small alternate bracts occur along the peduncles that resemble the leaves. Each daisy-like flowerhead has 10-18 ray florets that surround numerous disk florets; the ray florets are fertile and pistillate, while the disk florets are fertile and perfect. The petaloid rays of the ray florets are white, oblong in shape, and notched at their tips. The tiny corollas of the disk florets are yellow, tubular in shape, and 5-lobed at their apices; these lobes are triangular in shape. Alongside the disk florets, there are chaffy scales about 4 mm. in length. These scales are oblanceolate in shape and their tips are acute; sometimes these tips are awn-like. At the base of each flowerhead, there are 1-2 series of phyllaries (floral bracts) that are broadly oblong in shape. Individual phyllaries have convex central ridges that are light green, wide membranous margins that are white to light brown, and woolly pubescence; the phyllaries become chaffy with age. The foliage of this plant lacks a significant fragrance, although the crushed flowerheads are mildly fragrant (resembling apple-pineapple). The flowerheads are solid, lacking hollow centers. The blooming period usually occurs from late spring to mid-summer, lasting about 1-2 months, although some plants may bloom later in the year.
At maturity, the seedheads are ovoid in shape. The achenes are 1.5-2.5 mm. in length, oblanceoloid in shape, and slightly 4-angled; they are truncate at their apices, where they lack tufts of hair or significant scales. The sides of mature achenes have longitudinal ribs that are readily visible. The achenes are distributed to a limited extent by wind and probably by water at some locations. The root system consists of a shallow much-branched taproot or it is fibrous. Reproduction is by seeds.
Cultivation: The preference is full sun, moist to dry-mesic conditions, and a calcareous soil containing clay-loam, loam, silt, gravel, or sand. Drought tolerance is good. The seeds can remain viable in the ground for 10 years or more (Kay, 1971).
Range & Habitat: Field Chamomile has been found in scattered locations across Illinois (see Distribution Map), but this non-native plant is relatively uncommon within the state. It was introduced into North America from Eurasia, where it is native. In Illinois, habitats consist of fallow fields, roadsides, flood zones along drainage canals and retention ponds, vacant lots and abandoned homestead sites, and waste areas. Highly disturbed areas are preferred.
Faunal Associations: The flowerheads probably attract small bees, various flies (including Syrphid flies), and other insects. Both nectar and pollen are available as floral rewards to such visitors. Insects that feed destructively on Field Chamomile and other Anthemis spp. include Polymerus basalis (Red-Spotted Aster Mirid) and two aphids, Macrosiphoniella tanacetaria and Macrosiphoniella tapuskae. The former aphid is typically found on the flowerheads, peduncles, and upper stems, while the latter aphid is typically found on the lower leaves. The polyphagous caterpillars of a moth, Orthonama obstipata (The Gem), have been reported to feed on mayweeds by Covell (1984/2005). Field Chamomile belongs to the group of plants that are commonly referred to as mayweeds in Europe. The foliage of Field Chamomile is probably browsed sparingly by mammalian herbivores, while Canada Geese seem to avoid it. Because the seeds can pass through the gastrointestinal tracts of both cattle and pigeons and remain viable (Kay, 1971), these animals may spread them to new areas. It is also possible for the seeds to cling to the bottoms of the muddy shoes of people and the muddy hoofs of animals, by which means they can spread to new areas.
Photographic Location: Along a drainage canal and retention pond area in Champaign, Illinois.
Comments: Field Chamomile (Anthemis arvensis) is one of the plants that are commonly referred to as mayweeds. Examples of these species include Anthemis cotula (Dog Fennel), Chamaemelum nobile (Roman Chamomile), Matricaria recutita (German Chamomile), and Tripleurospermum perforatum (Scentless Chamomile). As a group, they are difficult to distinguish from each other. All of these species have daisy-like flowerheads that resemble those of Leucanthemum vulgare (Ox-Eye Daisy), but their foliage is deeply dissected (typically bipinnatifid). Field Chamomile can be distinguished from other mayweeds by its flat leaf-segments (rather than terete leaf-segments), by the presence and shape of the chaffy scales in its flowerheads, by the woolly pubescence of its foliage, and by the appearance of its achenes. The foliage of Field Chamomile lacks the pleasant fragrance of Roman Chamomile, nor does it possess the unpleasant odor of Dog Fennel. Similar to German Chamomile, the crushed flowerheads of Field Chamomile are mildly fragrant, but it has completely solid flowerheads, whereas the flowerheads of German Chamomile have interiors that are partly hollow.
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Miss Chen
2018年07月10日
Description: This herbaceous plant is a winter or spring annual that forms a low rosette of several basal leaves up to 4 cm. (1½") across. Individual basal leaves are 0.5–2 cm. (¼–¾") long and about one-third to one-half as much across; they are elliptic to broadly elliptic in shape, bluntly dentate toward their tips, and sessile. The leaf surface is medium green to reddish green (rarely red); its upper surface has sparse minute pubescence, while its lower surface is glabrous. Each rosette of basal leaves develops 1–15 flowering stalks that are 2.5 cm. (1") to 7.5 cm. (3") tall. These stalks are light green, reddish green, or red; they are short-pubescent, terete, and either erect or arching upward. The flowering stalks terminate in either solitary flowers or umbels of flowers (usually the latter); there are 2–10 flowers per umbel. Sometimes 1–2 secondary stalks will originate from an umbel of flowers to produce secondary umbels of flowers, making an inflorescence a partially compound umbel of flowers.
The secondary flowering stalks are similar to the primary flowering stalks, except they are usually shorter. The secondary umbels of flowers are similar to the primary umbels of flowers, except they tend to have fewer flowers. The pedicels of the flowers (or seed capsules) are 3–25 mm. (1/8–1") in length and erect to upwardly arching. Compared to the flowering stalks (peduncles), the pedicels are shorter and more slender, although they become longer as the seed capsules develop. Individual flowers are about 2 mm. across and 4 mm. long; each flower has a green calyx with 5 erect teeth, a white tubular corolla with 5 ascending lobes, 5 inserted stamens with short filaments, and a light green ovary with a single short style. The calyx is 5-angular from 5 ridges and it has sparse minute pubescence. The teeth of the calyx extend above the lobes of the corolla. Individual lobes of the corolla are lanceolate in shape. The teeth of the calyx are narrowly deltate to deltate in shape and a little shorter than the angular calyx-tube.
At the base of each umbel (or secondary umbel) of flowers, there are 2 or more leafy bracts that resemble the basal leaves, except they are smaller in size (less than 0.5 cm. or ¼" in length) and they lack teeth; sometimes they form a small rosette. The blooming period occurs from from early to late spring, lasting about 1 month. The flowers are inconspicuous. Afterwards, they are replaced by small seed capsules. These capsules are about 3 mm. long and ovoid in shape; each capsule eventually divides into 5 sections to release several seeds. These seeds are small enough to be blown about by the wind. Mature seeds are about 1 mm. long, 0.75 mm. across, 3-angled, and dark brown to black; the seed surface has a network of minute ridges and pits. The root system consists of a slender taproot. This plant reproduces by reseeding itself. It dies down no later than mid-summer.
Cultivation: The preference is full to partial sun, mesic to dry conditions, and a barren soil containing sand, gravel, clay, or rocky debris. Most growth and development occurs during the spring, which happens very quickly.
Range & Habitat: Western Rock Jasmine (Androsace occidentalis) is a native plant in Illinois, where it occurs occasionally in western and northern Illinois, while in the rest of the state it is uncommon or absent (see Distribution Map). This plant is more common in drier areas to the west of Illinois. In Indiana, Ohio, and Michigan, this plant is rare and state-listed as 'threatened' or 'endangered.' Habitats include gravel hill prairies, upland sand prairies, upland dolomite prairies, gravelly or sandy areas along railroads, roadsides, pastures, fallow fields, and waste ground. In Illinois, Western Rock Jasmine occurs in both higher quality natural areas and disturbed areas on exposed ground soil where it is dry and sunny.
Faunal Associations: This plant becomes more common in pastures that are moderately to heavily grazed by cattle as this reduces competition from taller and more aggressive plants (Patton & Nyren, 2015).
Photographic Location: Found on waste ground along an alley way in Urbana, Illinois. This dumped waste ground contained broken bricks and pieces of concrete.
Comments: This tiny plant has inconspicuous flowers and it is easily overlooked. When the stalks with umbels of flowers are produced, it fairly easy to identify, however. Western Rock Jasmine (Androsace occidentalis) is the only species of its genus that has been found in Illinois. Further to the west, however, there are several Rock Jasmine species (Androsace spp.). These more western species tend to be less weedy in appearance and they have showier flowers. Other common names for Androsace occidentalis are Western Rock Primrose and Western Fairy Candelabra. Sometimes this plant is simply referred to as Rock Jasmine, Rock Primrose, or Fairy Candelabra.
The secondary flowering stalks are similar to the primary flowering stalks, except they are usually shorter. The secondary umbels of flowers are similar to the primary umbels of flowers, except they tend to have fewer flowers. The pedicels of the flowers (or seed capsules) are 3–25 mm. (1/8–1") in length and erect to upwardly arching. Compared to the flowering stalks (peduncles), the pedicels are shorter and more slender, although they become longer as the seed capsules develop. Individual flowers are about 2 mm. across and 4 mm. long; each flower has a green calyx with 5 erect teeth, a white tubular corolla with 5 ascending lobes, 5 inserted stamens with short filaments, and a light green ovary with a single short style. The calyx is 5-angular from 5 ridges and it has sparse minute pubescence. The teeth of the calyx extend above the lobes of the corolla. Individual lobes of the corolla are lanceolate in shape. The teeth of the calyx are narrowly deltate to deltate in shape and a little shorter than the angular calyx-tube.
At the base of each umbel (or secondary umbel) of flowers, there are 2 or more leafy bracts that resemble the basal leaves, except they are smaller in size (less than 0.5 cm. or ¼" in length) and they lack teeth; sometimes they form a small rosette. The blooming period occurs from from early to late spring, lasting about 1 month. The flowers are inconspicuous. Afterwards, they are replaced by small seed capsules. These capsules are about 3 mm. long and ovoid in shape; each capsule eventually divides into 5 sections to release several seeds. These seeds are small enough to be blown about by the wind. Mature seeds are about 1 mm. long, 0.75 mm. across, 3-angled, and dark brown to black; the seed surface has a network of minute ridges and pits. The root system consists of a slender taproot. This plant reproduces by reseeding itself. It dies down no later than mid-summer.
Cultivation: The preference is full to partial sun, mesic to dry conditions, and a barren soil containing sand, gravel, clay, or rocky debris. Most growth and development occurs during the spring, which happens very quickly.
Range & Habitat: Western Rock Jasmine (Androsace occidentalis) is a native plant in Illinois, where it occurs occasionally in western and northern Illinois, while in the rest of the state it is uncommon or absent (see Distribution Map). This plant is more common in drier areas to the west of Illinois. In Indiana, Ohio, and Michigan, this plant is rare and state-listed as 'threatened' or 'endangered.' Habitats include gravel hill prairies, upland sand prairies, upland dolomite prairies, gravelly or sandy areas along railroads, roadsides, pastures, fallow fields, and waste ground. In Illinois, Western Rock Jasmine occurs in both higher quality natural areas and disturbed areas on exposed ground soil where it is dry and sunny.
Faunal Associations: This plant becomes more common in pastures that are moderately to heavily grazed by cattle as this reduces competition from taller and more aggressive plants (Patton & Nyren, 2015).
Photographic Location: Found on waste ground along an alley way in Urbana, Illinois. This dumped waste ground contained broken bricks and pieces of concrete.
Comments: This tiny plant has inconspicuous flowers and it is easily overlooked. When the stalks with umbels of flowers are produced, it fairly easy to identify, however. Western Rock Jasmine (Androsace occidentalis) is the only species of its genus that has been found in Illinois. Further to the west, however, there are several Rock Jasmine species (Androsace spp.). These more western species tend to be less weedy in appearance and they have showier flowers. Other common names for Androsace occidentalis are Western Rock Primrose and Western Fairy Candelabra. Sometimes this plant is simply referred to as Rock Jasmine, Rock Primrose, or Fairy Candelabra.
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