|
|
|
|
|
|
|
|
|
|
|
| Asclepias verticillata L. | Species Image Gallery (opens in a new window) |
||||||||||||||||||||||||||
| TAXONOMY | |||||||||||||||||||||||||||
| Family: | Asclepiadaceae | ||||||||||||||||||||||||||
| Genus: | Asclepias | ||||||||||||||||||||||||||
| Species Synonyms: | none | ||||||||||||||||||||||||||
| Common Names: | whorled milkweed eastern whorled milkweed |
||||||||||||||||||||||||||
| DISTRIBUTION | |||||||||||||||||||||||||||
| Canada: | southeastern Saskatchewan, southern Manitoba, southwestern Ontario | ||||||||||||||||||||||||||
| Saskatchewan: | southeastern Saskatchewan; near Estevan | ||||||||||||||||||||||||||
| Ecoregion: | Moist Mixed Grassland | ||||||||||||||||||||||||||
| HABITAT | |||||||||||||||||||||||||||
| Saskatchewan: | grazed pastures; dry clay or shale soil on south-facing, often eroded, grassland and alkaline coulee slopes | ||||||||||||||||||||||||||
| United States: | creeping juniper, little bluestem, western wheatgrass, white sagebrush | ||||||||||||||||||||||||||
| RARITY STATUS | |||||||||||||||||||||||||||
| Provincial
Status According to Harms (2003): |
Endangered |
||||||||||||||||||||||||||
| Nature Conservancy Status: | G5 S1 |
||||||||||||||||||||||||||
| Saskatchewan
Species at Risk Status: |
None |
||||||||||||||||||||||||||
| COSEWIC Status: | None |
||||||||||||||||||||||||||
| Whorled milkweed is endangered in Saskatchewan because it is extremely rare. In addition to this species being locally sparse, there are only two populations in Saskatchewan. Threats facing whorled milkweed include increased grazing pressure since both populations occur in grazed pastures. In addition, one of the sites is likely to have been affected by the construction of the Rafferty Dam. The last visit to the whorled milkweed populations recorded in the W. P. Fraser Herbarium was in 1997. It should be noted that this species is found within one mile of other provincial rarities: buffalo grass (Buchloe dactyloides) and whorled milkwort (Polygala verticillata) (Harms 1989). | |||||||||||||||||||||||||||
| Harms V.L. 1989. Distribution & Status of Provincially Rare Plants in the Souris River Valley, Southeastern Saskatchewan. Fraser Herbarium Technical Report 89-1. | |||||||||||||||||||||||||||
| SPECIES DESCRIPTION | |||||||||||||||||||||||||||
| Height: | 20 - 50 cm | ||||||||||||||||||||||||||
| Roots: | taproot thin, secondary roots many | ||||||||||||||||||||||||||
| Stem: | perennial, tufted, thin, to 0.5 cm wide hairless, milky latex present | ||||||||||||||||||||||||||
| Leaves: | whorls of 3 – 6, sessile, linear, 3 – 7 cm long, 1 – 2 mm wide, underside lightly woolly especially along margin, midrib prominent and white, upper surface hairless, margin rolled | ||||||||||||||||||||||||||
| Inflorescence: | umbels several, axillary or terminal, 8 – 10 -flowered; bracts small; flower stalks woolly hairy | ||||||||||||||||||||||||||
| Flowers: | sepals 5, greenish, reflexed at maturity; petals 5, yellowish, reflexed at maturity; corona hood white, alternate to petals, broadly oval, barely equalling anthers; horn sickle-shaped, incurved, protruding from corona hood; anthers and stigma fused; carpels separate from each other but fused with the style and stigma | ||||||||||||||||||||||||||
| Fruits: | pods erect, up to 12 cm long, without bumps; seeds numerous, flattened, silky-hairy | ||||||||||||||||||||||||||
| |||||||||||||||||||||||||||
