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权问薇
2018年03月27日
权问薇
[图片]一、时间选择 一般情况下，时间多在12月份，一直到翌年一月中下旬结束。 二、材料选择 这一步至关重要，对是否成活上午影响非常大。在对月季进行处理前，要选用容易成活、容易生根发芽的枝条作为本体进行嫁接，最好使用当年新长的枝芽。 三、具体步骤 首先，要将它的芽取下。取下来之后，用塑料膜与细绳进行捆绑，一定紧实一点并注意水分的多少，这样才能保持新鲜感。对于被嫁接的植物，接穗时最好是随插随剪，保证了植株的新鲜程度与成活率。剪月季枝是最好不要留下叶，一并去掉。嫁接完成后还要进行后续观察与记录，保证成功。 四、注意事项 接穗嫁接前需用植物激素进行浸泡至少六至八小时，因为这样能够促进其在剪根后自行进行伤口愈合，提供必要的营养支持。 同时，操作水平也一定要高，技术要达到足够熟练才行。 成功的保障之一就是砧木的选择，在选择砧木时要选择能够提供营养并及时输送养分的黄刺玫枝，也就是健康的枝条，因为它有着吸收有机物经及时输送的能力，所以砧木的选择很关键。 同时，操作那几天的水和温度等也都是很重要的。
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stone
2018年03月27日
stone
最近几年百合花已经在花友圈儿里很普及了，那么问题来了，百合花是怎么繁殖的，一般来说有三种方式，鳞片繁殖(附百合鳞片繁殖发芽图片)、子球分株，珠芽繁殖，而这三种方法各有自己的优缺点。 [图片]1.百合鳞片繁殖 选用秋季成熟的健壮种球，剥去外围的萎缩鳞片瓣后，健康的第二三轮鳞片(层)鳞片肥大，质厚，储存的营养物质最丰富，是最好的繁殖材料。剥取扦插用鳞片时，下手要轻，以免压伤鳞片表面，导致腐烂，每个鳞片基部最好能带上一部分盘基组织，以利于形成小新鳞茎。剥取下的鳞片用水冲洗干净，然后进行扦插。内层小而薄的鳞片不适宜做扦插繁殖材料，留下的中心小轴可单独栽培，自成一个新的鳞茎。 [图片]百合鳞片选好后，就是繁殖了，一般有两种方法，一种是将鳞片插入松软的介质1/3，另外一种是将松软的泥炭和鳞片混合起来装入塑料袋，然后在塑料袋里充满气，就可以了。 2.珠芽繁殖 亚洲百合，卷丹花后，尤其是消苞后会在植株叶片根部产生小鳞茎，叫做珠芽，如果是人为播种，花友需要注意的百合的种子寿命极短，贮存半年就会失去发芽能力，夏季采收成熟的百合珠芽(成熟的百合珠芽是紫黑色)，9月下旬至10月上旬即可播珠芽，播后覆土3厘米左右即可，百合珠芽的生长过程可参考第二段。 3.子球分株 这个就比较简单了，百合会自然在母株周围生出小百合球根，我们可以用这些小球根来繁殖，相对于鳞片繁殖节省了前面不少流程，直接进入小球养护模式。 就这三种百合方式来说，子球分株最为方便，也比较快，但是繁殖量比较少，而珠芽繁殖相信很多花友都没看到自己的百合有株芽，而卷丹百合之类，木有必要大量繁殖了。百合鳞片繁殖虽然时间长，但是可以量产。
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权问薇
2018年03月27日
权问薇
[图片]整形修剪 摘心疏蕾 如果摘心比较及时，它们就能开的比较快，所以要注意这一点，在开花之前进行摘心。如果花蕾过多，就会早造成花朵簇拥在一块的现象，但是这并不好看，所以要及时把多余的花蕾摘掉。摘掉之后，花儿不仅会更大，颜色也会更好看。 [图片]修枝 由于这种植物的萌发力是非常强的，所以适当的修枝才能让他们长的更好，如果不修剪的话，很影响观看的效果。修枝的时间一般选在花落之后或者秋天的时候，这段时间不会影响其正常生长。剪掉已经生病或长虫的枝条，这类枝条已经患病，不仅可能转染到旁边的枝条，还可能分走一部分养料。还要剪掉交叉的、徒长的、重叠的、过密的枝条，它们会影响整体的美观性，也会分出部分营养。 花期控制 这种花花芽分化的时候是在秋天，花期主要是通过调节期间的温度来调整。这里有两种方法，一种适用于想要它们提前开花，可以直接把盆栽的杜鹃放在室内养殖，除了温度保持在20-25℃，还要经常喷水，把周围的湿度控制在80%以上，这样45天之后就可以开花了。 第二方法适用于想让它们延迟开花的友友， 要将已经形成花蕾的杜鹃放在低温的位置，保持在2-4℃，盆土太干的时候再浇水，等夏天的时候再放回室外，大月半月就能开了。
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家里的二哈爱吃花
2018年03月27日
家里的二哈爱吃花
[图片]叶肿病 这个病出现的还算频繁，开始的时候叶子的正面会出现一些圆形的斑点，颜色基本上是淡黄色的。如果不及时处理的话，颜色会更黄。比较明显的部位是叶子的背面，背面又肥又肿，还呈现出淡黄的颜色。如果处理的不好的话，可能会导致叶柄也发生病变，可能也变得畸形肥厚，最后发病的部位会变成黑色，然后直接干枯脱落。 最初看到白色粉末状的物质，就要赶紧摘掉已经发病的部位，然后烧掉已经发病的部位，这样就不会让这部分的病菌传染到其他部位了。在发芽之前，最好喷施一点药剂，这样就可以减少发病的几率。 [图片]叶斑病 这种病算是比较常见的，叶子上面会出现深棕色的病斑，严重的话也会导致整片叶子枯萎脱落。由于这种病是非常可能出现的，所以最好要选择不易患病的品种。而且，要在发生之前进行防治。要先行喷施一点能防病的混合药液，这个操作最好是在5-8月的时候进行。一旦发现类似的病症，要加强管理，并且连续喷施7-8次药剂，每隔10天一次，为了不让它们黄化，还可以增加一点硫酸亚铁。 [图片]币厄病 遭遇这种病会在患病的位置出现比较密集的白色或粉色的质层，叶片上还可能产生螨瘿，这主要是由于蚜虫等小虫啃食过的地方被感染病菌，所以对蚜虫的防治也要尽量重视一点。和上述其他病症一样，如果发现病叶，要立刻摘下并烧毁，然后施药。
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权问薇
2018年03月27日
权问薇
[图片]扦插繁殖 时间 这种办法是比较适合种植少量杜鹃的花友的，这个办法操作起来是比较简单的，而且成活的也比较快，所以比较适合自家栽植的友友们。一般可以选择在5-6月的时候进行，这段时间植株长势比较好，温度也是比较合适的，所以在这段时间里，它们能成活的几率也比较大。 [图片]步骤 要选择比较健壮的枝条，这样可以保证它们的成活。枝条的长度在5-8cm左右就可以，然后剪掉下半部分的叶子，上面留下2、3片就可以。在插入基质之前，要事先涂上利于生根的生根粉等，然后插在透气性能比较好一点的基质之中，温度最好能控制在20-25℃，然后要遮掉一部分阳光，之后等待生根即可。 [图片]嫩枝繁殖 这种方法也是比较方便的，时间也可以选择5-6月的这段时间，由于温度比较适宜，也不用特意的去降温或者保暖，基本上自然的温度就能成活。这期间植株的生长情况也比较好，也没有进入休眠，吸取养分的能力比较好，所以爱成活一点。 接穗只需剪到3-4cm即可，最下面的部分要剪成楔形，然后接在毛娟做的砧木上，然后放在阴棚里面，再用塑料膜绑好，注意要把把塑料的和砧木套在一块，这样有利于保湿。 好了现在知道它们要如何繁殖了，到时候试一下吧。
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Miss Chen
2018年03月27日
Miss Chen
Description: This is a perennial wildflower about 2½-6' tall that is either unbranched or sparingly branched. The central stem is light gray-green, densely pubescent, terete, and rather stout. Alternate leaves occur at intervals along this stem. Individual leaves are up to 7" long and 6" across; they are oval-cordate in outline with 3-7 palmate lobes and crenate-dentate margins. Usually the middle lobes of the leaves are larger than the lateral lobes. The upper surface of these leaves is medium green and hairless to sparsely pubescent, while their lower surface is light gray-green and pubescent. The petioles are up to 6" long, light gray-green, and pubescent. Sometimes short secondary stems with small leaves develop from the axils of the leaves on the central stem. Flowers are produced either individually or in clusters of 2-3 from the axils of the leaves along the upper half of each plant. The pedicels of these flowers are rather short (up to ¾" long), light gray-green, and pubescent. Each flower is 1¼-2½" across, consisting of 5 light pink petals (obcordate in shape), 5 light gray-green sepals (ovate in shape) that are joined together at the base, a central reproductive column, and 3 light gray-green floral bracts (linear in shape). Individual sepals are about ½" in length, while individual floral bracts are about the same length; both floral bracts and sepals are short-pubescent. The stamens are located along the outer half of the reproductive column, while the styles are located at its tip. The anthers of the stamens are pale yellow or white. The blooming period occurs during the summer, lasting about 2 months. Individual flowers are short-lived and slightly fragrant. Afterwards, each fertile flower is replaced by a ring of carpels containing the seeds. The carpels are reniform and narrowly wedge-shaped; their outer edges are pubescent. Each carpel contains 2-4 seeds (about 3 mm. in length). The root system consists of a short stout taproot and rhizomes. Vegetative colonies of plants occasionally develop from the rhizomes. Cultivation: The preference is full or partial sun, moist to mesic conditions that are well-drained, and soil containing some loam or rocky material. Germination of the seeds requires scarification of the seed coat through mechanical means or by fire. In a dormant state, the seeds can be remain viable for up to 50 years. Cross-pollination with genetically distinct plants is required for the production of viable seeds. [图片]Range & Habitat: The native Kankakee Mallow has been found only in Kankakee County, where it is rare and state-listed as 'endangered' (see Distribution Map). Habitats consist of rocky riverbanks, woodland edges, open rocky woodlands, and abandoned fields. In all of these habitats within Illinois, the underlying bedrock of the thin soil consists of dolomite. Occasional wildfires are beneficial in maintaining populations of Kankakee Mallow as they stimulate the germination of seeds and reduce competition from woody vegetation. This wildflower has been cultivated successfully in gardens. Faunal Associations: Very little is known about floral-faunal relationships for this rare wildflower. The flowers are probably cross-pollinated by various long-tongued and short-tongued bees. White-Tailed Deer and other mammalian herbivores readily browse on the foliage. It may be necessary to place wire cages over individual plants in order to protect them from such animals. [图片]Photographic Location: A flower garden in Urbana, Illinois. Comments: The Kankakee Mallow has attractive flowers and foliage. This rare wildflower is endemic to Illinois, although an adventive population has been found in Indiana near a railroad. It is thought that members of a Chicago wildflower society may have established this population by throwing seeds of the Kankakee Mallow out of the window of a passing train during the early 20th century. There are some differences of opinion regarding the taxonomic classification of the Kankakee Mallow. It has been classified as the typical variety of a more western species, Iliamna rivularis (Mountain Hollyhock), and sometimes it is considered the same species as the more eastern Iliamna corei (Peter's Mountain Mallow). This last species was discovered on a sandstone outcrop in Virginia, where it was under attack by feral goats. The Kankakee Mallow differs from Peter's Mountain Mallow by having flowers that are fragrant. In general, mallows of the Iliamna genus differ from many other mallows by having 3 linear floral bracts behind the sepals of each flower.
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Miss Chen
2018年03月27日
Miss Chen
Description: This perennial vine is up to 30' long; it dies back to the ground each year. The stems are light green or light tan, stout, and smooth to prickly-bristly. The opposite leaves are up to 6" long and 4" across; smaller leaves are usually oval-cordate in shape, but larger leaves are palmate with 3 lobes (rarely with 5). These leaves have a rough texture and coarse serration along the margins; they are medium green or yellowish green on their upper surfaces, and whitish green below. The long petioles are light green or light tan, stout, and prickly-bristly. At the base of each petiole is a pair of lanceolate stipules. The hairiness or pubescence of the stems and leaves is variable, if it is present at all. Usually, there are small white hairs along the major veins on the leaf undersides; sometimes these veins are also prickly. American Hops is dioecious, with male (staminate) and female (pistillate) plants. The male plants produce drooping panicles of staminate flowers. These panicles are up to 12" long and 6" across; they contain numerous small flowers that are yellowish or whitish green. Each staminate flower has 5 sepals, 5 stamens, and no petals. It has a star-like appearance and spans about ¼" across, hanging downward from a slender pedicel that is often slightly pubescent. The non-sticky pollen is produced in great abundance and it is easily dispersed into the air. The female plants produce odd-looking cone-shaped spikes of pistillate flowers (aments) from the axils of the leaves. A spike of pistillate flowers is up to 3" long, 2" across, and ovoid in shape; it usually hangs downward from a slender peduncle. The pistillate spike consists of overlapping green bracts that are ovate; there is a pair of pistillate flowers tucked between each adjacent pair of bracts. Each pistillate flower consists of little more than an ovary with a sticky stigma that is long and slender. Both the male and female flowers bloom during the late summer for about 2 weeks. The male flowers quickly turn brown and wither away, while the fruits (or aments) of the female flowers persist longer and gradually turn brown. Each pistillate flower produces a capsule with a single seed that is resinous and aromatic. This vine reproduces by reseeding itself. [图片]Cultivation: The preference is partial or full sun, fertile soil, and moist to slightly dry conditions. This robust vine will also grow in poor soil that is rocky or gravelly. It can be quite aggressive and appears to have few problems with disease. Range & Habitat: The native American Hops is a common plant that occurs in most areas of central and northern Illinois. However, it less common or absent from many areas of southern Illinois (see Distribution Map). Other varieties of this vine also occur in Eurasia. American Hops occurs in openings of both upland and floodplain forests, woodland borders, thickets, and slopes of bluffs. In more developed areas, it is found along fence rows, vacant lots, areas along railroads, and miscellaneous waste areas. This plant favors areas that are more or less disturbed, whether from human activities or natural causes. It often clambers over surrounding vegetation, including shrubs and small trees. [图片]Faunal Associations: Pollination is by wind, rather than insects. However, the abundant pollen of the staminate flowers attracts flower flies (Syrphidae) and small bees. The caterpillars of several butterflies feed on hops (Humulus spp.), including Vanessa atalanta (Red Admiral), Polygonia interrogationis (Question Mark), Polygonia comma (Comma), and Strymon melinus (Gray Hairstreak). The caterpillars of the latter species feed on the fruits and developing seeds. The caterpillars of some moths also feed on hops; they include Eudryas grata (Beautiful Wood Nymph), Hydraecia immanis (Hop Vine Borer Moth), Hypena humuli (Hop Looper), and Cnephasia longana (Omnivorous Leaftier). Other insect feeders include Taedia hawleyi (Hop Plant Bug), Phorodon humuli (Hop Aphid), Psylliodes punctulata (Hop Flea Beetle), larvae of Lasioptera humulicaulis (Hop Stem Gall Midge), and the thrips Neohydatothrips beachae. Little information appears to be available about this vine's relationships to vertebrate animals, however it undoubtedly provides protective cover for many species of birds and mammals. [图片]Photographic Location: A sunny area along an abandoned railroad in Urbana, Illinois. This vine also occurred in partially shaded areas at the same locality. Comments: American Hops has some resemblance to grapevines (Vitis spp.), but it is a coarser and more bristly vine that flowers late in the year, while the latter flowers during the spring. The female fruit of hops is used to flavor beer and prevent decay during fermentation from bacterial processes. It is possible that the wind-dispersed pollen may cause allergic reactions in some people. There are both European and American varieties of this species, and it is quite possible that they have interbred in the wild. Consequently, they are often hard to distinguish. There is a variety of American Hops that has unlobed leaves. There is an invasive non-native species of hops that occurs in the wild, Humulus japonicus (Japanese Hops). This is an annual vine that has leaves with more lobes (5-7) than American Hops. Furthermore, the lobes of its leaves are more narrow and pointed.
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Miss Chen
2018年03月27日
Miss Chen
Description: This perennial herbaceous plant is 1-4' tall and unbranched. The central stem is light green to purple, terete, glabrous to short-pubescent below, and short-pubescent above. About 6-30 alternate leaves are distributed evenly along the length of the stem; the leaves remain the same size, or become slightly smaller in size, as they ascend the stem. Individual leaves are 1½–4" long ¼–1¼" across; the length and width of these leaves varies with the robustness of the plant and the local ecotype or variety. Leaf shape is elliptic, lanceolate-elliptic, lanceolate, or lanceolate-ovate, while leaf margins are sparsely dentate, sparsely denticulate (minutely dentate), or smooth. The upper leaf surface is pale-medium to medium green and glabrous, while the lower leaf surface is pale green and glabrous to short-pubescent. Leaf bases are rounded to narrowly wedge-shaped, while their tips are acute. The leaves are either sessile or they clasp the stem; a few leaves may have short petioles (3 mm. or less) that are appressed against the stem. The central stem terminates in a panicle of flowerheads that is often corymb-like in shape; a large panicle may have more than one corymb-like division. The size of these panicles is 3-20" long and 5-10" across; small panicles are sometimes more wide than they are across, while large panicles are longer in length than they are across. The branches of each panicle are light green, terete, short-pubescent, and largely naked; a few leafy bracts up to ¼" long may be present. The terminal branches produce individual flowerheads about ¾-1¼" across. Each flowerhead has 30-80 ray florets and no disk florets. The petaloid extensions (or rays) of these florets are bright yellow and narrowly oblong in shape; their tips are 5-toothed and truncate. The base of each flowerhead is surrounded by narrow green phyllaries in 2-3 series. The outermost phyllaries are the smallest. These phyllaries are glabrous or short-hairy; sometimes they have short glandular hairs. The blooming period occurs from mid-summer to early fall, lasting about 3-4 weeks for a colony of plants. In the absence of cross-pollination from other plants, the florets are self-fertile. Shortly afterwards, the florets are replaced by small achenes with sessile tufts of light brown hair. The achenes are about 2.5–3 mm. in length, bullet-shaped, ribbed along their sides, and truncate at their apices. They are distributed by the wind. The root system is fibrous, sometimes forming clonal offsets. On older plants, a small caudex may develop. [图片]Cultivation: The preference is full sun to light shade, mesic to dry conditions, and either sandy or rocky soil. This plant dislikes hot summer weather (90°F or higher temperatures). Plant size can vary considerably depending on the habitat, weather, and local ecotype. Range & Habitat: Northern Hawkweed is occasional in northern Illinois, where it is native (see Distribution Map). It also occurs in Eurasia, although the latter continental mass has varieties that are distinct from those in North America. Habitats include sandy upland savannas, sand prairies, stabilized sand dunes, openings in sandy or rocky woodlands, sandy thickets, sandy fields, and roadsides. Northern Hawkweed can be found in either high quality or disturbed habitats. It probably benefits from occasional wildfires if this reduces competing woody vegetation. Faunal Associations: Various bees and probably other insects visit the flowerheads for nectar and/or pollen, including Halictid bees. Some aphids suck plant juices from the flowering stems and other parts of hawkweeds (Hieracium spp.); these species include Hyperomyzus inflatus, Nasonovia ribisnigri (Currant-Lettuce Aphid), Uroleucon hieracicola (Hawkweed Aphid), and Uroleucon sonchi (Sow-Thistle Aphid). Another insect, the plant bug Lygus rubroclarus, feeds on hawkweeds and other members of the Aster family. These plants are also suspected hosts of Schinia bina (Bina Flower Moth). Among vertebrate animals, the Ruffed Grouse and Wild Turkey eat the seeds and leaves of hawkweeds to some extent; the Cottontail Rabbit and White-Tailed Deer also browse on the leaves (Martin et al., 1951/1961). [图片]Photographic Location: The wildflower garden of the webmaster in Urbana, Illinois. Comments: Northern Hawkweed is one of the showier native hawkweeds (Hieracium spp.) because it has larger flowerheads (about 1" across) than most. It also produces more leaves along its stems, and the branches of its inflorescence are short-pubescent, rather than glandular-hairy. The taxonomy of this hawkweed, at least in North America, is somewhat confused. In addition to Hieracium umbellatum (Northern Hawkweed), this plant is also referred to as Hieracium canadense (Canada Hawkweed) and Hieracium kalmii (Kalm's Hawkweed). The view taken here is that Hieracium umbellatum is a highly variable species that subsumes both Eurasian and North American plants. The primary difficulty in North America is that leaf width and the amount of dentition along leaf margins are highly variable. Populations of plants in northeastern United States and southeastern Canada tend to have wider leaves with more strongly defined teeth, while populations of plants in the upper midwest of the United States and south-central Canada tend to have more narrow leaves with poorly defined teeth. In Eurasia, this plant tends to have even more narrow leaves than what is observed in North America. These and other variations have led to the description of different varieties and subspecies that have varied in their popularity across time. Another common name of Hieracium umbellatum is Narrow-Leaved Hawkweed.
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Miss Chen
2018年03月27日
Miss Chen
Description: This perennial wildflower is 1-3½' tall, producing a leafy central stem that is unbranched and more or less erect. The central stem is light green and more or less covered with spreading hairs; some hairs along the upper section of this stem may be glandular, otherwise they are non-glandular. Several alternate leaves occur along the lower three-fourths of this stem, becoming gradually smaller in size and more widely spaced as they ascend toward the inflorescence. The leaf blades are 2-6" long and ½-2" across, lanceolate-oblanceolate to ovate-obovate with smooth to nearly smooth margins. Some larger leaves may have widely spaced dentate teeth that are poorly defined. The upper surface of the leaf blades is medium green and hairy, while the lower surface is pale green and hairy. Each leaf tapers gradually into a petiole-like base and its tip is relatively blunt. Both the central stem and leaves contain a milky latex. [图片]The central stem terminates in an elongated panicle of flowerheads up to 1' long and ½' across. Individual flowerheads are ½-¾" across, consisting of 30-60 yellow ray florets and no disk florets. Around the base of each flowerhead, 12-20 floral bracts (phyllaries) are arranged in a single series. Individual floral bracts are light green, linear in shape, and often glandular-hairy. The branches of the inflorescence are light green to dull purple and glandular-hairy; there are often a small leafy bracts (less than 1" in length) where these branches divide. The glandular hairs along the branches of the inflorescence and the floral bracts of the flowerheads are often black. The blooming period occurs from late summer to early fall for about 3-4 weeks. The florets are self-fertile in the absence of cross-pollination. The florets are replaced by achenes with tufts of tawny hair. Individual mature achenes are about 1/8" (3 mm.) long, narrowly cylindrical in shape, truncate at the apex, and dark brown. The root system is fibrous and rhizomatous; older plants may have a short underground caudex. Small colonies of plants are formed occasionally by the spreading rhizomes. A small rosette of basal leaves may be present during the winter after the flowering stalk with alternate leaves dies down. Stem & LeavesCultivation: The preference is full sun to light shade, mesic to dry-mesic conditions, and soil containing loam, sand, or rocky material. The size of individual plants and the abundance of their flowerheads is highly variable. Range & Habitat: The native Rough Hawkweed is occasional in most areas of Illinois (see Distribution Map). Habitats include rocky upland woodlands, bluffs, wooded slopes, woodland openings, savannas and sandy savannas, partially shaded ledges, woodland borders, and sandy roadsides. This wildflower benefits from occasional disturbance to reduce competition from woody vines, shrubs, and trees. Faunal Associations: Surprisingly little information is available for hawkweeds (Hieracium spp.) about their floral-faunal relationships. The flowerheads are probably cross-pollinated by long-tongued bees and other insects; both nectar and pollen are available as floral rewards to such visitors. Hawkweeds are suspected host plants for the caterpillars of Schinia bina (Bina Flower Moth). The seeds or leaves are occasionally eaten by the Wild Turkey and Ruffed Grouse, while the foliage is browsed sparingly by the Cottontail Rabbit and White-Tailed Deer (Martin et al., 1951/1961). However, the bitter white latex and hairiness of the foliage does not make this species a preferred source of food for such animals. Photographic Location: A deciduous woodland near an artificial lake at a state park in east-central Illinois. Comments: This is one of several native hawkweeds (Hieracium spp.) in Illinois that have unbranched leafy stems and yellow flowerheads. Generally, they prefer semi-shaded wooded areas that are sandy or rocky, although Rough Hawkweed also occurs in woodlands with fertile loam. It is very similar in appearance to Hieracium gronovii (Gronovius' Hawkweed), but the latter species has spindle-shaped achenes with tapered upper tips (rather than truncate upper tips), relatively fewer florets per flowerhead (about 20-40), and leaves that are located toward the base of its central stem. Another similar species, Hieracium canadense (Canada Hawkweed), has larger flowerheads (¾-1¼" across) with more florets per flowerhead (40-100), inflorescence branches that are short-pubescent (rather than glandular-hairy), and more leaves along each central stem (often 12 or more). There are some hawkweeds that have been introduced from Europe, but their leaves are arranged in basal rosettes during the blooming period, unlike the native hawkweed species.
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Miss Chen
2018年03月27日
Miss Chen
Description: This perennial herbaceous wildflower is 3–6½' tall, sending up one or more erect leafy stems from its root system. The stems are light green, faded light yellow, or faded light brown; they are terete, stiffly short-pubescent, and sparingly branched above. Most of the leaves are located along the lower half of the primary stems, where they are opposite. Smaller alternate leaves occur sparingly along the upper primary and secondary stems. All of these stems are erect to ascending. The lower to middle leaves are up to 6" long and 5" across; they are broadly oblong to oval-ovate in shape with margins that are slightly serrated to doubly serrated. To a limited extent, the leaf margins are also horizontally undulate. The leaves abruptly contract to narrowly winged petioles up to 2" long. These petioles have short stiff hairs. The leaf blades are medium green or yellowish green above, and light green below. The upper blade surface is sparsely covered with minute stiff hairs, providing it with a rough texture. The lower blade surface has short stiff hairs along the primary veins and a sparse covering of minute stiff hairs between the veins. The leaves have a prominent central vein and two prominent lateral veins; the latter curve toward the leaf tips. [图片]The upper stems terminate in either solitary flowerheads or small loose clusters of 2-3 flowerheads on long naked peduncles up to 1' long. These flowerheads tend to occur at different heights from the ground. The peduncles are similar to the stems, except they are a little more narrow in diameter. The flowerheads are held erect or at an angle facing partly upward; they span about 2-3" across. Each flowerhead has 10-20 ray florets and a central disk of numerous disk florets. The widely spreading petaloid rays are bright yellow and oblong in shape. The corollas of the disk florets are about 6 mm. (¼") long, tubular in shape with 5 upper lobes, and dark red above. The divided styles of the disk florets are bright yellow, while their tubular anthers are dark red. The ray florets are sterile, while the disk florets are perfect. Surrounding the base of each flowerhead, there are floral bracts (phyllaries) in 3 series; these bracts differ in size and they are appressed together. Individual floral bracts are light green and broadly oblong in shape; their tips are obtusely pointed or rounded. The margins of these bracts are toothless and ciliate; their outer surfaces between the margins are sparsely short-pubescent. The blooming period occurs during early autumn, lasting about 3-4 weeks. Afterwards, fertile disk florets are replaced achenes about 4 mm. in length. These achenes are oblong-obovate, somewhat flattened, brown, and short-pubescent primarily toward their apices. Each achene has a pair of lanceolate scales about 2 mm. long at its apex. However, these scales are early-deciduous. Because the seeds are dispersed primarily by gravity, they usually do not travel far from the mother plant. The root system consists of a crown of fibrous roots and short rhizomes. Clonal offsets are produced sparingly from the short rhizomes. Cultivation: This plant prefers full or partial sun and mesic to dry-mesic conditions; it adapts to different soil types, including those that contain sand, loam, clay, and rocky material. It is easy to cultivate this plant in gardens and it remains more or less erect, rather than flopping over. Because of its short rhizomes, it is a less aggressive spreader than some sunflower species. [图片]Range & Habitat: Silphium Sunflower has been found in only 2 counties of southern Illinois (Alexander and St. Clair counties), where it is native and rare (see Distribution Map). It may be extirpated from Alexander county, but several populations of this plant still persist in St. Clair county. Illinois lies along the northern range-limit of this species. Silphium Sunflower is endemic to south-central and central United States, where it is found primarily in Arkansas, Missouri, and Tennessee. Habitats include sand prairies, upland prairies and glades, upland savannas, openings in rocky woodlands, low sandy ground along streams, roadsides, and fallow fields. This sunflower is found in both high quality natural areas and disturbed sites. In wooded habitats, it benefits from occasional wildfires. Destruction of habitat by development and invasion of exotic species are the primary threats to this rare plant in Illinois (Molano-Flores, 2004). [图片]Faunal Association: While little is known about floral-faunal relationships for this particular sunflower species, considerable information is available about other sunflower species and sunflowers in general. Similar species of sunflowers attract such flower-visiting insects as bumblebees, long-horned bees (Melissodes spp.), leaf-cutter bees (Megachile spp.), Halictid bees (Agapostemon spp., Lasioglossum spp.), Andrenid bees (Andrena spp.), dagger bees (Heterosarus spp.), plasterer bees (Colletes spp.), cuckoo bees (Epeolus spp., Triepeolus spp.), miscellaneous wasps, Syrphid flies (Eristalis spp., Toxomerus spp.), bee flies (Exoprosopa spp.), miscellaneous butterflies, and miscellaneous skippers (Robertson, 1929, and others). Some bees are specialist pollinators (oligoleges) of sunflowers; they include Melissodes agilis, Dufourea marginata, Andrena accepta, Andrena aliciae, Andrena helianthi, and Pseudopanurgus rugosus. Other insects feed destructively on the leaves, stems, roots, seeds, and florets of sunflowers. These species include weevils, long-horned beetles, leaf beetles, billbugs, seed weevils, larvae of leaf-miner flies, larvae of gall midges, plant bugs, aphids, treehoppers, mealybugs, larvae of Tortricid moths, larvae of Noctuid moths, larvae of other moths, grasshoppers, and flower thrips. The caterpillars of some butterflies feed on sunflowers; these species include Chlosyne gorgone (Gorgon Checkerspot), Chlosyne nycteis (Silvery Checkerspot), and Vanessa cardui (Painted Lady); see Bouseman & Sternburg, 2001; Charlet & Gavloski, 2011. Some vertebrate animals use sunflowers as a source of food. Upland gamebirds and songbirds eat their nutritious seeds; the Mourning Dove, Bobwhite Quail, American Crow, Eastern Goldfinch, Common Grackle, Eastern Meadowlark, White-breasted Nuthatch, and various sparrows are examples of such birds (Lewis, 1993; Martin et al., 1951/1961). White-tailed Deer and domesticated grazing animals like to feed on the young stems and leaves of these plants (Georgia, 1913; Martin et al., 1951/1961). The seeds of sunflowers are dispersed to a limited extent by birds; sometimes they drop the seeds during flight before they consume them. [图片]Photographic Location: The wildflower garden of the webmaster in Urbana, Illinois. Comments: The Silphium Sunflower (Helianthus silphioides) is often overlooked in wildflower guidebooks and it is little-known by members of the public. This is partly because, for a long time, this sunflower was considered a variety of the Purple-disk Sunflower (Helianthus atrorubens). However, the Silphium Sunflower differs from the latter by having fewer long hairs on its stems, more narrow and less winged petioles, and achenes that are pubescent primarily toward their apices, rather than throughout. The Purple-disk Sunflower is found primarily in SE United States; it does not occur in Illinois. Scientific synonyms of the Silphium Sunflower include Helianthus atrorubens pubescens and Helianthus kentuckiensis. Other common names of this sunflower include Rosinweed Sunflower and Ozark Sunflower. The common names, Silphium Sunflower and Rosinweed Sunflower, refer to the superficial similarity of this sunflower to the prairie wildflower, Silphium integrifolium (Rosinweed). It also resembles Heliopsis helianthoides (False Sunflower) to a significant extent, but the flowerheads of Silphium Sunflower are borne on longer naked stalks than those of the False Sunflower, and it usually blooms later in the year than the latter species.
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