Asclepias nyctaginifolia
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Asclepias nyctaginifolia |
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| A.Gray |
Asclepias nyctaginifolia is a species of silk plants ( Asclepias ) from the subfamily of silk plants (Asclepiadoideae). It occurs in the southwestern United States and northern Mexico.
description
Appearance and leaf
Asclepias nyctaginifolia grows as a low, perennial herbaceous plant that reaches heights of 15 to 20 cm (or 10 to 40 cm, exceptionally also up to 60 cm). The relatively slender, finely downy, hairy stems, rising or lying, are close together at the base and branch a little above the base. The opposite arranged leaves are divided into a petiole and a leaf blade. The petiole is 1 to 3 cm long. The blade base is broadly obtuse angled or rounded, and ends quite abruptly in a wedge shape in the petiole. The membranous, dark green, simple leaf blade is egg-shaped to almost rhomboidal with a length of 6 to 10 cm and a width of 2 to 4 cm with a blunt or pointed upper end. Both leaf surfaces are finely hairy, especially the underside. The leaf margins are usually wavy.
Inflorescence and flower
The flowering period in the home area extends from May to August. The pendant on some of the top almost without inflorescence stem node standing (Nodien) inflorescences contain only a few flowers. The approximately 2 cm long flower stalks are stiff and finely hairy.
The comparatively large, hermaphrodite flowers are radially symmetrical and five-fold. The five finely downy hairy sepals are ovate-lanceolate and only fused at their base with a length of about 4 mm. The five petals are usually bent back, the corolla lobes are 12 to 14 mm (12 to 16 mm) long. They are greenish yellow in color, with a tinge of purple on the outside. The short conical, about 0.5 mm high and 1 mm wide stalked gynostegium is light greenish-cream colored. The staminal corolla lobes are 8 to 11 mm (about 1 cm) long and 2 to 3 mm wide at the top and oval or oblong and rounded at their base. The upper edge of the staminal corolla lobes is rounded and very slightly wavy. They protrude from the gynostegium by 4 to 7 mm. The inner secondary processes are horn-shaped and almost completely fused with the staminal corolla lobes; only a pointed, tooth-like protrusion about 1 mm long is still free and is slightly shorter than the staminal corolla lobes. The stylus head is broadly conical, about 2 mm long and 3 mm wide.
Fruit and seed
The upright, standing on curved stems follicles are thick fusiform tipped at a length of 3 to 5 cm and a diameter of 1.5 cm to 3 and briefly above. They are finely hairy or glabrous. The seed is not known.
Synecology
Asclepias nyctaginifolia is an important food plant for the caterpillars of the common butterfly Danaus gilippus .
Occurrence
Asclepias nyctaginifolia occurs only in the southwestern US states of Arizona , California and New Mexico, and in the northern Mexican state (state of Sonora ).
It grows there along erosion channels, temporary watercourses , springs, depressions, slopes and grasslands as well as in sparse forests and also along roads through the desert. Asclepias nyctaginifolia thrives at altitudes between 500 and 2000 meters.
swell
literature
- Robert E. Woodson, Jr .: The North American Species of Asclepias L. In: Annals of the Missouri Botanical Garden. Volume 41, Number 1, pp. 1-211, St. Louis, Mo., 1954 Scanned at biodiversitylibrary.org . ( Asclepias nyctaginifolia on pp. 155–156)
- Eric Sundell: Asclepiadaceae Milkweed Family. In: Journal of the Arizona-Nevada Academy of Science. Volume 27 (2), 1993, pp. 169-187: PDF
Individual evidence
- ↑ a b c Woodson, 1954, pp. 155/6.
- ↑ a b c Sundell, 1994, p. 179.
- ^ Southeastern Arizona Wildflowers and the Plants of the Sonoran Desert. (Pictures of flowers!)
