Asclepias uncialis
| Asclepias uncialis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Asclepias uncialis |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Asclepias uncialis | ||||||||||||
| Greene |
Asclepias uncialis is a species of silk plants ( Asclepias ) from the subfamily of the silk plants (Asclepiadoideae).
features
Vegetative characteristics
Asclepias uncialis is a small, perennial , upright plant with a rhizome- like rhizome. The slender, herbaceous shoots are ascending or lying down and only 5 to 20 cm long. Several, densely packed, very sparsely downy, hairy shoots that are unbranched grow out of the rhizome. The constantly compared to alternate irregularly arranged on the stems leaves are short stalks to very short (1 to 5 mm long), and very different in shape along the drive. The lower leaf blades are egg-shaped, the higher blades change rather abruptly to a linear-lanceolate shape. The outer end is obtuse to acute, the base obtuse to rounded. They are 1 to 2 cm long, 2 to 7 mm wide and very finely hairy.
Inflorescence and flowers
The little-flowered inflorescences are terminal or nearly terminal laterally on the uppermost nodes and sessile, rarely also with short stalk. The stalked flowers are comparatively small, the very slender flower stalks are 1 to 1.5 cm long and finely hairy. The sepals are ovate-lanceolate, about 2 mm long and sparsely hairy and downy. The corolla is wheel-shaped and strongly curved back, purple-pink petals . The tips are about 4 mm long. The single-row, pale pink to yellowish corolla is sessile. The tips of the (staminal) secondary crown are short-sac-shaped, about 1.5 mm long and flattened at the upper end. The shape is created by rolling the tips inwards. At the “seam” of the sack-like structure, the edges are bent at right angles and drawn out into triangular, pointed projections. The tips of the secondary crown are slightly shorter than the gynostegium . The secondary process on the inside of the tip starts at about mid-height. The process, which is flat on the inside, is swollen, ovoid and only slightly longer than the tip. The stylus head is about 1 mm long and 1.5 mm wide.
Fruits and seeds
The follicles stand upright on U-shaped bent stems; they are about 4 to 6 cm long. Usually only one fruit develops per stem, rarely two fruits.
Similar species
Asclepias uncialis is closely related to Asclepias cutleri and Asclepias brachystephana ; all species are very small and restricted to dry locations.
Geographical distribution and ecology
The distribution area of Asclepias uncialis extends over the US states of Arizona , Colorado , Nevada , New Mexico , Oklahoma , Texas , Utah and Wyoming . It grows in dry, sandy or stony soils at an altitude of 1100 to 2150 m above sea level. It blooms there in May and June. The first flowering plants were already collected at the end of March. The flowers stay open for four to eight days. The strong floral scent is described as "rose scent" or "scented of citrus". They produce a lot of nectar. The fruits ripen in 40 to 60 days after fertilization. Since the rhizome-like rootstock produces several shoots that are often widely spaced apart, a limited vegetative reproduction is also considered possible.
Taxonomy and systematics
The taxon was first described by Edward Lee Greene in 1880 . In 1941, Bassett Maguire described the taxon Asclepias ruthiae ; the epithet honors his wife Ruth Maguire. Robert Everard Woodson considered both taxa to be valid species in 1954. In contrast, Eric Sundell reduced Asclepias ruthiae in 1994 to a mere variety of Asclepias uncialis . John T. Kartesz and Kanchi Natarajan Gandhi raised the rank of Asclepias ruthiae back to a subspecies in 1991 . The Plant List accepts these two subspecies. As synonyms of subspecies ruthiae be Asclepias eastwoodiana Barneby and Asclepias sanjuanensis healing, Porter & Welsh viewed (1989).
- Asclepias uncialis subsp. uncialis : This subspecies is very small, the shoots are only 5 to 10 cm long. The leaves are lanceolate to linear. The downy hair is limited to the leaf margins and the leaf veins. The flowers are comparatively small, the petals 3 to 4 mm long. The tips of the secondary crown have well-developed triangular appendages on the edges. The horn-shaped secondary process is flattened on the inside and ovoid in outline. The subspecies uncialis is restricted to Arizona, Colorado, New Mexico, Oklahoma, Texas, Utah, Wyoming. It grows there at 1500 to 2150 m altitude in light forests and desert bushes.
- Asclepias uncialis subsp. ruthiae (Maguire) JTKartesz & Gandhi . The shoots are 10 to 20 cm high with mostly broadly ovate, broadly elliptical or almost round leaves, which slowly change to narrowly ovate or broadly lanceolate leaves upwards. The edges are woolly hairy, the upper and lower sides short woolly hairy to bald. The flowers are comparatively large, the petal tips are 4 to 6 mm long. The corners of the secondary crown have only indistinct to moderately developed triangular appendages at the edges. The secondary process on the inside of the tip of the secondary crown is roughly finger-shaped.
The holotype is kept at Utah State University. The subspecies ruthiae is restricted to Arizona, New Mexico, Nevada, and Utah. It grows there in desert bushes and pinyon pine - juniper communities at an altitude of 1100 to 1900 m.
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. 180/1)
- Robert Everard 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 (p. 167 )
- Daniela Roth: Species account for Asclepias sanjuanensis. Navajo Natural Heritage Program, PO Box 1480, Window Rock, AZ 86515. PDF
- Bruce Hoagland: Survey of extant and potential populations of Asclepias uncialis, Ptilimnium nodosum, Thalictrum arkansum, and Agalinis skinneriana. Final Report, Project E-43. US Fish and Wildlife Service, New Mexico PDF
- Karin Decker: Asclepias uncialis Greene (wheel milkweed): A Technical Conservation Assessment. Prepared for the USDA Forest Service, Rocky Mountain Region, Species Conservation Project, 2006 PDF
- James Riser, Eric Roalson: Populations Genetics and Species Boundaries in the Dwarf Milkweed Group (Asclepias uncialis-ruthiae-eastwoodiana-sanjuanensis Asclepiadoideae: Apocynaceae). Conference Botany 2013, July 27-31, New Orleans Abstract
Individual evidence
- ^ Edward Lee Greene: Notes on Certain Silkweeds. In: Botanical Gazette , Volume 5, 1880, pp. 65–65 Online at www.biodiversitylibrary.org (pp. 64/5)
- ^ Bassett Maguire, Robert E. Woodson, Jr .: Two New Asclepiads from the Southwestern United States. In: Annals of the Missouri Botanical Garden , Vol. 28, No. 2, 1941, pp. 245-248 JSTORE (p. 245)
- ↑ John T. Kartesz, Kanchi Natarajan Gandhi: Nomenclatural Notes for the North American Flora. VIII. In: Phytologia , Volume 71, No. 4, 1991, pp. 269-280 Online at www.archive.org (p. 270)
- ↑ 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 23, 2013.
- ^ Rupert Charles Barneby: A new species of Asclepias from Nevada. In: Leaflets of Western Botany , Volume 4, 1945, 210-211 Online at www.biodiversitylibrary.org .
- ↑ Kenneth Heil, James Marc Porter, Stanley Larson Welsh: A new species of Asclepias (Asclepiadaceae) from northwestern New Mexico. In: Great Basin Naturalist , Volume 49, 1989, pp. 100-103 PDF .
- ↑ Utah State University Asclepias ruthiae holotype
