Asclepias asperula
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Asclepias asperula |
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| ( Decne. ) Woodson |
Asclepias asperula is a species of silk plants ( Asclepias ) in the subfamily of the silk plants (Asclepiadoideae) within the family of dog poison plants (Apocynaceae). It is widespread in the United States and Mexico.
description
Vegetative characteristics
Asclepias asperula is a deciduous, perennial , herbaceous plant that reaches heights of 20 to 60 cm. It forms a strong, horizontal rhizome from which several strong, ascending or prostrate stems grow every year in spring , which are covered with thin, soft hairs ( trichomes ).
The leaves, which are arranged irregularly alternately on the stems, are short stalked (3 to 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 tapered Spreitenbasis and a pointed outer end. It is thin and firm, only slightly hairy and usually folded more or less along the middle.
Generative characteristics
In the terminal, golden inflorescence , several flowers are very crowded. The only slightly hairy inflorescence stem can be very short, but also up to 10 cm long. The slender flower stalk is 1.5 to 2.5 cm long and tomentose.
The hermaphrodite, radially symmetrical , five-fold flowers are cup-shaped with a diameter of over 1 cm. The five sepals are lanceolate to ovate and 4 to 5 mm long. They have fine downy hairs. The five petals are 9 to 12 mm long, light yellowish green, on the outside playing into purple red. They stand almost vertically and bend upwards about the lower third. The single-row secondary crown has no free stem. The 8 to 10 mm long tips of the secondary crown are curled inwards, and the edges touch each other. They thus form an elongated tubular structure that is also curved in a J or C shape. At first they stand vertically from the stem, descend a little and curve upwards in the middle and then stand upright or are slightly curved inward. They are about as high as the gynostegium . They are greenish-cream to purple-red. The secondary process, triangular in outline and flat on the inside, starts relatively high on the inside of the tubular lobes and is completely enclosed. The strongly flattened stylus head is 2 mm long and 5 mm wide.
The upright on curved stems are follicles with a length of 4 to 13 cm and a diameter of 1.0 to 2.5 cm oblong-pointed-egg-shaped. Their surface is smooth and finely haired. The seeds are flattened ovate (7 × 8 mm). The light brown head of hair is up to 3 cm long.
ecology
The flowering period extends from March to August. The pollination is usually performed by large bees . Asclepias asperula is one of the main food plants of the caterpillars of the monarch butterfly ( Danaus plexippus ).
Occurrence
Asclepias asperula occurs in the USA ( Arizona , California , Colorado , Idaho , Kansas , Nevada , New Mexico , Oklahoma , Texas and Utah as well as Nebraska ) and in northern Mexico ( Chihuahua , Coahuila , Durango , Hidalgo , Nuevo León , San Luis Potosí , Sonora and Tamaulipas ).
Asclepias asperula prefers stony, chalky or sandy, relatively dry soils in prairies and plains, from where it also spreads into pastureland .
Systematics
The first description of this species was in 1844 by Joseph Decaisne Prodromus Systematis Naturalis Regni Vegetabilis , 8, p. 522 under the name Acerates asperula . Eric Woodson placed it in 1954 in Annals of the Missouri Botanical Garden , 41 (1), p. 193 in the genus Asclepias . Asclepias capricornu subsp. occidentalis Woodson is only a synonym of Asclepias asperula subsp. capricornu (Woodson) Woodson .
The species Asclepias asperula is divided into two subspecies by Woodson (1954) :
- Asclepias asperula (Decne.) Woodson subsp. asperula : The leaves are linear to lanceolate, the peduncle is relatively long, the tips of the corolla are usually dark purple-red. Distribution: Colorado and western Texas to Utah, Arizona, Nevada and neighboring areas in Idaho and California. In Mexico, the subspecies occurs in Tamaulipas westward to Sonora, and southward to San Luis Potosí and Hidalgo.
- Asclepias asperula subsp. capricornu (Woodson) Woodson : The leaves are usually broadly lanceolate. There is no or only a very short peduncle, the tips of the corolla are usually greenish-cream-colored. Distribution: eastern and central Oklahoma, Texas and southern Kansas.
supporting documents
literature
- Eric Sundell: Asclepiadaceae Milk Weed Family , In: Journal of the Arizona-Nevada Academy of Sciences , 27, Tempe, Ariz. 1994, pp. 169–187: PDF (pp. 173/4)
- 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 (pp. 192-196)
Individual evidence
- ^ School of Biological Sciences University of Texas Austin .
- ^ WH Calvert: Patterns in the spatial and temporal use of Texas milkweeds (Asclepiadaceae) by the monarch butterfly (Danaus plexippus L.) during fall, 1996. , In: Journal of the Lepidopterists Society , 53 (1), 1999, p. 37–44: PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ United States Department of Agriculture - Plants Profile: Asclepias asperula (Decne.) Woodson spider milkweed
- ↑ RB Kaul, SB Rolf Meier and JJ Esch: The distribution and reproductive phenology of the Milkweeds (Asclepiadaceae: Asclepias and Cynanchum) in Nebraska. , In: Transactions of the Nebraska Academy of Sciences , 18, 1991, pp. 127–140: Abstract ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. .
- ^ Joseph Decaisne: Asclepiadeae . In: Augustin Pyramus de Candolle, Alphonse de Candolle: Prodromus systematis naturalis regni vegetabilis, sive, Enumeratio contracta ordinum generum specierumque plantarum huc usque cognitarium, juxta methodi naturalis, normas digesta. Volume 8, pp. 553–665, Paris, Treuttel & Würtz, 1844. Online at www.biodiversitylibrary.org (p. 522)
- ^ Asclepias asperula at Tropicos.org. Missouri Botanical Garden, St. Louis
