Asclepias exaltata
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Asclepias exaltata (English poke milkweed ) is a species of silk plants ( Asclepias ) from the subfamily of silk plants (Asclepiadoideae).
features
Vegetative characteristics
Asclepias exaltata is a perennial plant with a fleshy, whitish taproot. The herbaceous shoots die off every year after the vegetation period and sprout again from the taproot in the following year. As a rule, only one shoot is formed per rhizome or taproot. This is comparatively strong, unbranched and 40 to 100 cm high, under very favorable location conditions even up to 180 cm high. The shoots are bare, or lines with inconspicuous downy hairs run down the shoots from the nodes. The stalked leaves are arranged opposite one another. The stems are 0.5 to 1.5 cm long. The thin, membranous leaf blades are ovate to elliptical, or elongated-elliptical with a short, narrow tip; the base is broadly rounded. They are 10 to 20 cm long, 2 to 11 cm wide and sparsely hairy or bald on top; the underside is gray-green and hairy. The leaf veins have a slight purple tint; they stand out clearly from the green of the leaf blade.
Inflorescence and flowers
The solitary, pendulous inflorescences are almost terminal at the uppermost nodes . They are few to many flowers (up to 10 flowers) and relatively open, and have a stiff, 0.3 to 8.5 cm long, purple-colored stem. The five-fold hermaphrodite flowers are zygomorphic and have a double flower envelope. The flower stalk is slender and 3 to 5 cm. The flowers are of medium size with ovate-lanceolate, approximately 5 mm long, bare sepals . The corolla is wheel-shaped with back curved petal tips. The 8 to 12 mm long tips are whitish with a pink or purple tint. The single-row, whitish corolla has a short stalk, the short stalk is inverted to cylindrical and about 2 mm long and just as wide. The 3.5 to 4 mm long tips of the staminal secondary crown are tubular-hood-shaped and more or less clearly serrated at the edges. The horn-shaped secondary process leans in the middle below the tip of the secondary crown, is about twice as long as this, and inclines over the stylus head. The stylus head is cylindrical, 3 to 3.5 mm long and wide. The flower produces abundant nectar and gives off a rather unpleasant smell to the human nose.
Fruits and seeds
The follicles stand upright on curved stems and are narrow spindle-shaped, 12 to 15 cm long and 1.5 to 2 cm wide. They are smooth and essentially hairless. The seeds are broadly elliptical, 7 to 9 mm long, and have a white, 3 to 4.5 cm long head of hair.
Geographical distribution and (syn-) ecology
The range of the species extends over large areas of the eastern and central USA ( Alabama , Connecticut , Delaware , Georgia , Illinois , Indiana , Iowa , Kentucky , Maine , Maryland , Massachusetts , Michigan , Minnesota , Mississippi , New Hampshire , New Jersey , New York , North Carolina , Ohio , Pennsylvania , Rhode Island , South Carolina , Tennessee , Vermont , Virginia , West Virginia and Wisconsin ) to southern Canada ( Ontario and Québec ). The species grows in damp forests, bushes and meadows. It blooms from May to August.
The flowers attract numerous insects with their abundant nectar. The species is also a food plant for the caterpillars of the monarch butterfly ( Danaus plexippus ) and the bear moth Euchaetes egle .
Taxonomy and systematics
The taxon was first classified by Carl von Linné in 1762. Asclepias phytolaccoides G.F. Lyon ex Pursh (1813) is a more recent synonym . The English vulgar name poke milkweed is derived from this name . Asclepias exaltata is accepted as a valid taxon by the Plant List .
supporting documents
literature
- Robert E. Woodson, Jr .: The North American Species of Asclepias L. In: Annals of the Missouri Botanical Garden , Vol. 41, No. 1, 1954, pp. 1-211, St. Louis, Mo. URL
Individual evidence
- ↑ Carl von Linné: Species Plantarum, Edition 2. Volume 1, 784 S., Holmiae, Impensis Direct. Laurentii Salvii, 1762-63. Online at www.biodiversitylibrary.org (p. 313)
- ^ Frederick Pursh: Flora Americae Septentrionalis: or, A systematic arrangement and description of the plants of North America. Containing, besides what have been described by preceding authors, many new and rare species, collected during twelve years travels and residence in that country. London, printed for White, Cochrance, and Co., 1813 Online at www.biodiversitylibrary.org
- ^ Rafael Govaerts (ed.): World Checklist of Selected Plant Families (in review): Ceropegia. Published in: The Plant List. A working list of all plant species. Royal Botanic Gardens Kew, Missouri Botanical Garden, accessed December 2, 2011.
