Asclepias amplexicaulis
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Asclepias amplexicaulis ( Clasping Milkweed or Blunt-leaved Milkweed ) is a species of the genus silk plants ( Asclepias ) from the subfamily of the silk plants (Asclepiadoideae). It is native to North America.
features
Vegetative characteristics
Asclepias amplexicaulis is an upright, perennial , herbaceous plant with stiff, unbranched, and bare stems that reach 40 to 90 cm (30 to 100 cm) high. The surface is waxy and whitish. The membranous to slightly leathery leaves are sessile or sessile and opposite. There are two to five pairs of leaves that are far apart. The leaf blades are broadly ovate, ovate to oblong-lanceolate; they grow to about 7.5 to 12.5 cm (3 to 5 inches ) long . They are usually about two to three times longer than they are wide. The spreading tip (apex) is broadly rounded up to an obtuse angle, often ending in a small patch Spitzchen (mucronat). The base is broadly heart-shaped and includes the stem (amplexicaul). The leaves are more or less intensely greenish and often have wavy edges. The midrib is often reddish in color.
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Inflorescence and flowers
The solitary inflorescences are almost always terminal, rarely they arise laterally from the uppermost leaf axils. They stand upright, are hemispherical, relatively open and multi-flowered with about 10 to 30 flowers. Usually only one inflorescence per plant is formed, rarely more. The inflorescence stalks are stiff and 10 to 30 cm long; if they arise laterally from a leaf axil, they are a little shorter. Usually the inflorescence sits about 30 cm above the top pair of leaves. The flower stalks are also stiff, 2 to 5 cm long and slightly curved upwards and towards the center of the umbellate inflorescence. The stem of the inflorescence and the flower stalks are often slightly reddish. The five-fold hermaphrodite flowers are zygomorphic and have a double flower envelope. They are comparatively large and wheel-shaped with the tips of the petals bent back almost completely . The bald sepals are lanceolate and 3 to 5 mm long, the petal lobes are 9 to 11 mm long. The latter are greenish and tinged more or less purple or pink. The gynostegium or the secondary crown is purple, pale purple or rose-colored and has a short stalk. The stem is cylindrical and about 2 mm long. It measures about 2.5 to 3 mm in diameter. The tips of the staminal secondary crown are elongated tubular and about 5 mm long. The upper edge can be drawn out to a blunt point on the outside, or the edge can also be slightly serrated. The horn-shaped secondary processes lie on the inside of the lobes over half of the length, and protrude about half the length of the tubular lobes. They are flattened and curved inwards over the stylus head at the upper end. The stylus head is broadly cylindrical, 3 to 3.5 mm long and about 3 mm wide.
Fruits and seeds
The thin, spindle-shaped, often paired follicles stand upright on downward-curved stems. They are 10 to 16 cm long, with a maximum diameter of 1 to 2 cm just below the center. The outside is smooth, bare and greenish. The seeds are broadly ovate and 6 to 9 mm long. The pale yellow-brown head of hair becomes 4 to 6 cm long.
Similar species
Asclepias amplexicaulis is similar to the common milkweed ( Asclepias syriaca ), but it has larger, stalked leaves that do not enclose the stem. This species is also much larger.
Geographical distribution and ecology
The range of the species extends from the North American east coast (from New Hampshire to Florida) to Nebraska, Kansas, Oklahoma and Texas in the west.
The species occurs in open pine, juniper or oak forests, in prairies and old, already fortified sand dunes. From these locations it can also spread to clearings, adjacent pastureland, roadsides and railroad tracks. The specimens grow mainly in sandy or gravel soils. The flowering period is from March to September (April to June).
Taxonomy
The taxon was first described by James Edward Smith . Asclepias amplexicaulis occasionally hybridizes with Asclepias humistrata .
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
- ↑ a b Jason Sing Hurst, Ben Hutchins: Identification of Milkweeds in Texas. Texas Parks and Wildlife Department, 2015 PDF
- ↑ a b c d Minnesota Wildflowers: Asclepias amplexicaulis (Clasping Milkweed)
- ↑ James Edward Smith: The natural history of the rarer lepidopterous insects of Georgia: including their systematic characters, the particulars of their several metamorphoses, and the plants on which they feed. Collected from the observations of Mr. John Abbot. Vol. 1, J. Edwards, London, 1797 (online at www.biodiversitylibrary.org) Plate 7 , description p. 13
- ^ The International Plant Index: Asclepias amplexicaulis Sm.