Asclepias subverticillata
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Asclepias subverticillata |
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| ( A.Gray ) Vail |
Asclepias subverticillata is a species of silk plants ( Asclepias ) from the subfamily of silk plants (Asclepiadoideae).
features
Vegetative characteristics
Asclepias subverticillata is a perennial , herbaceous , upright plant with a woody rhizome . The mostly branched, rarely unbranched shoots reach heights of 15 to 120 cm. The dwarfed side shoots are sterile and only have very small leaves. The shoots are more or less hairy, the hairs arranged in lines emanate from the nodes . Occasionally the hair is absent and the shoots are bare. The leaves are short-stalked, with 3 to 5-whirled, rarely opposing arrangement on the inflorescences-bearing shoots. The leaves are opposite on the sterile dwarf shoots. The membranous leaf blades are linear, 2 to 13 cm long, 1 to 4 mm wide, and glabrous to sparsely hairy. The leaf stalks are 1 to 2 mm long. The edges are slightly bent.
Inflorescence and flowers
The inflorescences are usually solitary, rarely in pairs on the uppermost nodes . The inflorescences are few to many-flowered with slender, 1.5 to 3 cm long stems. The stalked corolla is relatively small, the slender stems are 5 to 8 mm long. The slightly downy hairy to bald sepals are narrow-triangular and 1.5 to 2 mm long. The corolla is wheel-shaped with strongly curved back, 3 to 5 mm long petals . It is white, rarely tinged with greenish-purple. The whitish or yellowish secondary crown sits on a relatively thin, 1 mm long, cylindrical stem. The hood-shaped tips of the secondary crown are approximately square to obovate in outline and about 1.5 mm long. The five horn-shaped secondary processes on the basal inner side of the tips are needle-shaped, slightly longer than the tips and incline at the outer end over the stylus head . The stylus head is cylindrical, about 1.5 mm long and just as wide.
Fruits and seeds
The paired follicles stand upright on stems pointing upwards. They are narrowly spindle-shaped, 5 to 9 cm long and 6 to 8 mm thick. The outer sides are smooth, glabrous or very weakly hairy. The seeds are broadly elliptical and 7 to 8 mm long with a 2 cm long, white head of hair.
Geographical distribution and ecology
The species is native to the central United States ( Arizona , Colorado , Idaho , Kansas , Missouri , Nebraska , Nevada , New Mexico , Oklahoma , Texas , Utah, and Wyoming ) and northern Mexico ( Chihuahua , Coahuila , Durango , Nuevo León, and Sonora ). It occurs on sandy and rocky plains at 900 to 2400 m above sea level. It blooms there from June to August.
All parts of the plant are very poisonous. In grazing animals, 0.2 lb (<100 g) per 100 lb (approx. 45 kg) live weight is fatal. The highest toxicity is reached before the seeds ripen and then decreases as the plant slowly dries out. But there have also been reports of losses of cattle due to hay containing Asclepias subverticillata . The poisoning is caused by neurotoxins .
Taxonomy and systematics
The taxon was first described by Asa Gray in 1877 as Asclepias verticillata var. Subverticillata . Anna Murray Vail upgraded the taxon to a species in 1898. The Plant List accepts it as a valid species.
supporting documents
literature
- Eric Sundell: Asclepiadaceae Milkweed Family. , In: Journal of the Arizona-Nevada Academy of Science , Vol. 27, No. 2, 1993, pp. 169-187. PDF (p. 180)
- 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 (pp. 65–67)
Individual evidence
- ↑ United States Department of Agriculture - Plants Profile: Asclepias subverticillata (A. Gray) Vail horsetail milkweed
- ^ MK McCarty, CJ Scifres: Western Whorled Milkweed and Its Control. In: Weed Science , Volume 16, No. 1, 1968, pp. 4-7 URL
- ^ T. Garland, Alberto C. Barr: Poisonous Plants and Other Natural Toxicants. 585 pp., CABI, 1998 Online at Google Books
- ^ Asa Gray: Contributions to the Botany of North America. In: Proceedings of the American Academy of Arts and Sciences , Volume 12, 1877, pp. 51–84, Boston Online at www.biodiversitylibrary.org (p. 71)
- ^ Anna Murray Vail: Studies in the Asclepidaceae - III. In: Bulletin of the Torrey Botanical Club , Vol. 25, 1898, pp. 171-182, New York. Online at www.biodiversitylibrary.org (p. 154)
- ↑ Rafael Govaerts (ed.): World Checklist of Selected Plant Families (in review): Asclepias. Published in: The Plant List. A working list of all plant species. Royal Botanic Gardens Kew, Missouri Botanical Garden, accessed May 12, 2013.
