Asclepias michauxii
Asclepias michauxii, or Michaux's milkweed, is a species of flowering plant in the family Apocynaceae. It is endemic to the southeastern United States, where it occurs from southeastern North Carolina south to peninsular Florida and west to eastern Louisiana.
Taxonomy
Asclepias michauxii was first described by Joseph Decaisne in 1844. It has been associated with several synonyms, including Oligoron tenuifolium Raf. and Asclepias suaveolens Leconte ex Decne.
The species has historically been misidentified as Asclepias cinerea or Asclepias longifolia, particularly in North Carolina collections.
Description
Asclepias michauxii is an erect to reclining perennial herb growing approximately 10–40 cm (4–16 in) tall. The stems are unbranched, purplish, and bear vertical lines of hairs, exuding milky latex when damaged.
Leaves are mostly opposite, sessile, and linear, typically 5–11 cm (2–4.5 in) long, with smooth surfaces or occasionally hairy veins beneath.
The flowers are borne in rounded terminal umbels. Individual flowers are greenish-white tinged with pink, about 1 cm long, with strongly reflexed corolla lobes. The corona consists of five hood-and-horn structures, with elongated, pointed horns surrounding the central reproductive column.
The fruit is a slender follicle containing seeds equipped with tufts of hairs for wind dispersal.
Distribution and habitat
This species is endemic to the southeastern United States, occurring in Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, and South Carolina.
It is primarily associated with pine savannas and flatwoods, including both wet seepage areas and drier sandy uplands.
Ecology
Asclepias michauxii grows in fire-maintained ecosystems and is adapted to open pine savanna habitats. Like other milkweeds, it produces latex and is pollinated by insects, with seeds dispersed by wind.
Its persistence is influenced by habitat conditions such as fire regime; fire suppression and conversion of natural pine savannas to dense plantations can negatively affect populations.
Conservation
Asclepias michauxii has a global conservation status of G4 (apparently secure) according to NatureServe, though its status varies regionally.
It is considered critically imperiled (S1) in Louisiana and extirpated (SH) in North Carolina, while remaining more secure in other parts of its range such as Georgia (S5).
Threats include habitat loss, fire suppression, and alteration of pine savanna ecosystems.
Etymology
The species epithet michauxii honors the French botanist André Michaux, who conducted extensive botanical exploration in North America.
References
michauxii Category:Flora of the United States Category:Endemic flora of the United States Category:Flora of the Southeastern United States Category:Plants described in 1844