Asclepias curtissii
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Asclepias curtissii |
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Asclepias curtissii (English Curtiss' milkweed) is a species of the genus silk plants ( Asclepias ) from the subfamily of the silk plants (Asclepiadoideae). The area of the species is limited to South Florida. It is very rare and the occurrences are highly fragmented. It also only grows on well-drained sandy soils. The specific epithet honors Allen Hiram Curtiss , an American botanist who researched the flora in Florida.
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features
Vegetative characteristics
Asclepias curtissii is a perennial plant with a fleshy, whitish taproot. The herbaceous shoots die off every year after one growing season and sprout again from the taproot in the following year. As a rule, only one shoot is formed per rhizome or taproot. Occasionally no shoot is formed for a year and the plant does not sprout again until the following year. The shoots initially growing upright, later lying down or leaning against other plants are comparatively slender, simple and sparsely branched. The branches usually result from injuries to the end shoot. They are 30 to 70 cm (up to 120 cm: 4 feet) long and are inconspicuously fluffy hairy or bald. The milky juice is white, sticky and thick. An average of 14 nodes are formed, the internodes are 2.4 cm long on average. The deep green, mostly opposite, very rarely alternating leaves are stalked, the stems 4 to 7 mm long. On average, 22 leaves are formed per plant; up to a maximum of 55 sheets. The leaf blades , usually with slightly wavy edges, are broadly elliptical, ovate or approximately square with an obtuse-angled tip. The end of the leaf can also be rounded, with a spiky indentation, the base is broadly rounded. The blades are 2 to 5 cm long, 1.5 to 3 cm wide, tight-skinned and glabrous.
Inflorescence and flowers
The few (≈ 3), single, stalked inflorescences are multi-flowered (20–30 flowers) and dome-shaped, and arise laterally at some of the uppermost nodes . The inflorescence stalks are slender, 2.5 to 4 cm long and finely hairy. The five-fold hermaphrodite flowers are zygomorphic and have a double flower envelope. The flower stalk is thin and 1 to 1.5 cm long and finely hairy. The flowers are rather small. All flowers of an inflorescence bloom more or less synchronously. The anthesis lasts about 5 days. The sepals are narrow-lanceolate and 2.5 to 3 mm long. The corolla is wheel-shaped with almost completely turned back corolla lobes , these are pale green, greenish-white to white and about 6 mm long. The single-row, white or cream-colored corolla is almost sessile (i.e. sessile), broadly inverted and measures 0.5 mm in length and 2 mm in width. The hood-shaped tips of the staminal secondary crown are oblong-lanceolate and pointed. They are 4.5 to 5 mm long, greenish white to pale pink. However, the color is constant within a plant. The horn-shaped secondary process is much shorter than the lobes and lies over half the length of the lobes inside. It is sharply curved inwards at the upper end. The hood-shaped tips contain nectar produced by nectar bags. The stylus head is broadly conical with a flattened top and about 1.5 mm long and 3 mm wide.
Fruits and seeds
The mostly solitary and upright, rarely paired follicles are spindle-shaped and 14 cm long. The follicle fruit takes about 60 days to ripen and contains about 50 seeds on average. The seeds have a head of white hair.
Similar species
The inflorescence of the species resembles a white-flowered Asclepias tuberosa , but is certainly more closely related to Asclepias purpurascens .
Geographical distribution and (syn-) ecology
Asclepias curtissii Gray is limited to two plant communities without exception: scrub and scrubby flatwood ; both occur almost exclusively in Florida. Both plant communities require well-drained, deep, sandy and nutrient-poor soils. The scrub community is made up of Pinus clausa and Quercus geminata . Quercus inopina , Quercus myrtifolia , Quercus chapmanii and Ceratiola ericoides . The "scrubby flatwood" community consists of Pinus palustris , Pinus elliottii , the aforementioned xerophytic oak species, various lichens ( Cladonia spp. And Cladina spp.) And the grass Aristida sp.
The species needs a sunny location and blooms in its natural habitat from April to August, some plants also until October. The flowers produce a lot of nectar and therefore attract butterflies, including Danaus gilippus and the monarch butterfly ( Danaus plexippus ). The plant is also food for the caterpillars of these butterfly species, which eat the leaves. The caterpillars of a bear moth species Neoplynes eudora also feed on the leaves of Asclepias curtissii . However, the butterflies observed most frequently on the flowers were representatives of the thick-headed butterflies (Hesperiidae). Were observed Thorybes Pylades , VIBEX Polites , Atalopedes campestris , Hylephila Phyleus , Erynnis zarucco , Erynnis horatius , Wallengrenia Otho and Panoquina ocola . Often were Bläulinge (Lycaenidae) observed: were identified Hemiargus ceraunus , Strymon melinus and Fixinia Favonius . The attached pollinia prove that these butterflies are the potential pollinators of the flowers. In one case a specimen of Wallengrenia otho with 9 attached pollinia was observed, in another case a specimen of Hylephila phyleus with 8 attached pollinia. But other insects have also been observed on the flowers, albeit far less often. There were also ants on the flowers to drink nectar.
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The plants seem to get very old, as do some other species of the genus Asclepias , e.g. B. Asclepias meadii . In one garden, one specimen had survived for 25 years before it was observed. The specimen did not produce a shoot every year. However, they cannot reproduce vegetatively.
Taxonomy and systematics
The taxon was first classified by Asa Gray in 1883 . The type specimen was collected in 1879 by Allen Hiram Curtiss near Titusville, on the east coast of Florida. It is now kept in the US National Herbarium in Washington, DC.
A more recent synonym is Asclepias aceratoides George Valentine Nash (1895). As the name already Asclepias aceratoides M.A.Curtis was awarded (1849), hit Nash in 1896 the new name Asclepias arenicola Nash before nomen novum. Edward Lee Greene transferred Asclepias arenicola Nash to the genus Oxypteryx ; Oxypteryx arenicola (Nash) Greene is thus also a synonym for Asclepias curtissii . John Kunkel Small transferred Asclepias curtissii to the genus Oxypteryx in 1933 , and in 1954 Robert Everard Woodson reassigned the taxon to the genus Asclepias . The Plant List accepts the taxon as a valid species.
Danger
The species is very rare in the area, the occurrences are not only strongly fragmented due to the severe destruction of the habitats, but also due to the location requirements of the species. It is therefore considered endangered. However, their rarity may be overestimated, as many specimens only sprout every two years, and some specimens may have even longer periods of rest.
supporting documents
literature
- Robert E. 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
- Patrick Mondo, Kristen D. Marshall Mattson, Cynthia C. Bennington: The Effect of Shrubs on the Establishment of an Endangered Perennial (Asclepias curtissii) Endemic to Florida Scrub. In: Southeastern Naturalist , Volume 9, No. 2, 2010, pp. 259-274 doi : 10.1656 / 058.009.0205
- Francis E. Putz, Maria Minno: The pollination biology and ecology of Curtiss' milkweed. (Asclepias currissii). Nongame Wildlife Program Project GFC-86-027. 1995 preview at www.academia.edu .
Individual evidence
- ↑ a b Native Florida Wildflowers
- ↑ Rebecca G. Harvey, Patricia L. Howell, Carol Morgenstern, and Frank J. Mazzotti: Native Habitats for Monarch Butterflies in South Florida. Publication # WEC266
- ^ Asa Gray: Contributions to North American Botany. In: Proceedings of the American Academy of Arts and Sciences , Volume 19, 1883, pp. 1-96, Boston Online at www.biodiversitylibrary.org
- ↑ George Valentine Nash: Notes on some Florida Plants. In: Bulletin of the Torrey Botanical Club , Volume 22, 1895, pp. 141-161, New York. Online at www.biodiversitylibrary.org (p. 154)
- ↑ George Valentine Nash: Botanical Notes: Asclepias arenicola nn In: Bulletin of the Torrey Botanical Club , Volume 23, 1895, pp. 253-254, New York. Online at www.biodiversitylibrary.org
- ^ Edward Lee Greene: On the classification of Asclepias. In: Pittonia , Volume 3, 1897, pp. 231-238, Washington, DC Online at www.biodiversitylibrary.org (p. 253)
- ^ John K. Small: Manual of the southeastern flora. 1554 S., New York, 1933 (p. 1072).
- ↑ 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 12, 2013.
- ↑ Plants Profile - Asclepias curtissii A. Gray Curtiss' milkweed
- ^ Daniel B. Ward, Daniel F. Austin, Nancy C. Coile: Endangered and Threatened Plants of Florida, Ranked in Order of Rarity. In: Castanea , Volume 68, No. 2, 2003, pp. 160-174 URL .
