Asclepias subulata
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Asclepias subulata |
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Asclepias subulata is a species of the silk plant family (Asclepiadoideae). It is the only succulent species from the genus of silk plants ( Asclepias ).
features
Vegetative characteristics
Asclepias subulata forms slender, somewhat fragile sub -shrubs , some of which are succulent and reach heights of 1 to 2 m. The blue-green, glabrous and smooth shoots are 3 to 5 mm in diameter. The branches are covered with opposite leaves only at larger intervals and on the younger parts. The linear, sessile, bare leaves are 2 to 8 cm long and 1 to 2 mm wide. They fall off very quickly and in the dry seasons, at the time of flowering the plant is without leaves.
Inflorescence and flower
The inflorescence is formed in the area of the branch tips and consists of five to twelve flowers. It has a diameter of about 3 to 6 cm. The few inflorescences appear from around April until late autumn. The relatively short, stiff inflorescence stem measures 1 to 2 cm and is usually finely hairy. The slender flower stalks are 1 to 1.5 cm long and also finely hairy. The flower is comparatively large. The sepals are lanceolate and 3 mm long. The corolla is yellowish white, the corolla lobes (about 9 to 11 mm long and lanceolate) are completely turned back. The gynostegium is creamy white and has a short stem. This is conical, measures 1 mm in length and 2.5 mm in width. The staminal, 9 to 10 mm long corolla lobes are folded up like a bag. The horn-shaped secondary processes are somewhat shorter than the staminal corolla lobes, are completely enclosed by them and can hardly be seen from the outside. The stylus head is conical in shape, with a length of 3 to 3.5 mm and a width of 4 to 5 mm.
Fruit and seed
The spindle-shaped follicles are 8 to 10 cm long and about 1 cm in diameter. They are finely hairy or glabrous. The oval, up to 6 mm long seeds have a yellow-brown head of hair 3 to 4 cm in diameter.
Geographical distribution and habitat
This species is found in the US states of Arizona , California and Nevada and is called desert milkweed here . In Mexico, the incidence is on Baja California (Baja California) and the northwestern state of Sonora limited.
It occurs there on dry, sandy or rocky soils at altitudes of about 50 m to about 850 m.
ecology
The plant is poisonous in all parts. In its area, it is an important food plant for the monarch butterfly ( Danaus plexippus ) and the related butterfly Danaus gilippus strigosus .
literature
- Focke Albers & Ulli Meve (eds.): Succulent lexicon Volume 3 Asclepiadaceae (silk plants). Ulmer, Stuttgart 2002 ISBN 978-3-8001-3982-8 .
- Eric Sundell: Asclepiadaceae Milkweed Family. Journal of the Arizona-Nevada Academy of Science, 27 (2): 169-187, 1993 PDF
- Robert E. Woodson, Jr .: The North American Species of Asclepias L. Annals of the Missouri Botanical Garden, 41 (1): 1-211, St. Louis, Mo., 1954 URL (description of A. linaria on p. 118–120)
