Asclepias asperula
Asclepias asperula
Asclepias asperula is a species of the genus milkweed ( Asclepias ) in the subfamily of the milkweed family ( Asclepiadoideae ) within the family of the dogbane family ( Apocynaceae ). It is widespread in the U.S. and in Mexico.
- 5.1 Literature
- 5.2 Notes and references
Description
Vegetative characteristics
Asclepias asperula is a deciduous, perennial, herbaceous plant that reaches the plant height of 20 to 60 cm. It forms a strong, horizontal rhizome from which each year grow more strong, ascending or prostrate stems in spring, with thin, soft hairs ( trichomes ) are occupied.
The irregularly alternate arranged on the stems leaves are short stalked ( 3-7 mm long). The leaf blade is at a length of 10 to 20 cm and a width of 1 to 3 cm lanceolate - linear to broad - lanceolate with a blunt or pointed Spreitenbasis and a pointed outer end. She is thin and firm, only slightly hairy, and usually more or less folded along the center together.
Generative features
In the terminal, doldigen inflorescence several flowers are very crowded. The only slightly hairy inflorescence stem may be very short, but also up to 10 cm long. The slender flower stem is hairy 1.5 to 2.5 cm long, tomentose.
The hermaphrodite, radial symmetry, five petals are cup-shaped with a diameter of about 1 cm. The five sepals are lanceolate to ovate and 4-5 mm long. They have a fine downy hair. The five petals are 9-12 mm long, pale yellowish green, playing on the outside of the purple. You are almost perpendicular and turn off after about the bottom third up. The row Nebenkrone has no free handle. The 8 to 10 mm long tip of the corona are rolled inwards, and the edges are touching. Thus, they form a elongated tubular structure, which is also C-shaped or J- curved. They are first vertically from the stem off, climb a bit and bend in the middle up and then stand erect or slightly curved inwards. They are about as high as the Gynostegium. They are greenish- cream to purple. The triangular in outline, inside flat secondary extension is relatively high on the inside of the tubular tip, and is completely enclosed. The strongly flattened stylus head is 2 mm long and 5 mm wide.
The upstanding stems on curved follicles are elongated pointed ovoid with a length of 4 to 13 cm and a diameter of 1.0 to 2.5 cm. Its surface is smooth and finely hairy. The seeds are ovate flattened (7 x 8 mm). The light brown head of hair is up to 3 cm long.
Ecology
The flowering period extends from March to August. Pollination is usually by large bees. Asclepias asperula is one of the main food plants of the caterpillars of the monarch butterfly (Danaus plexippus).
Occurrence
Asclepias asperula comes in the U.S. (Arizona, California, Colorado, Idaho, Kansas, Nevada, New Mexico, Oklahoma, Texas and Utah, and Nebraska) and northern Mexico (Chihuahua, Coahuila, Durango, Hidalgo, Nuevo Leon, San Luis Potosi, Sonora and Tamaulipas ) ago.
Asclepias asperula preferred stony, calcareous or sandy, relatively dry soils in prairies and plains, from where they spread in grasslands.
System
The first description of this kind was made in 1844 by Joseph Decaisne Prodromus systematis Naturalis Regni Vegetabilis, 8, pp. 522, under the name Acerates asperula. Eric Woodson she put 1954 in Annals of the Missouri Botanical Garden, 41 (1 ), pp. 193 in the genus Asclepias. Asclepias capri cornu subsp. occidentalis Woodson is just a synonym.
The species Asclepias asperula is from Woodson (1954 ) is divided into two subspecies:
- Asclepias asperula ( Decne. ) Woodson subsp. asperula: The leaves are linear to lanceolate, the peduncle is relatively long, the tip of the corona are usually dark purple. Distribution: Colorado and western Texas to Utah, Arizona, Nevada, and adjacent areas in Idaho and California. In Mexico, the subspecies occurs in Tamaulipas westward to Sonora, and southward to San Luis Potosi and Hidalgo ago.
- Asclepias asperula subsp. capri cornu ( Woodson ) Woodson: The leaves are usually broad - lanceolate. You have no or only a very short peduncle, the tip of the corona are usually greenish- cream color. Distribution: Eastern and central Oklahoma, Texas and southern Kansas.