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| Asclepias verticillata L. | Species Image Gallery (opens in a new window) |
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| TAXONOMY | |||||||||||||||||||||||||||
| Family: | Asclepiadaceae | ||||||||||||||||||||||||||
| Genus: | Asclepias | ||||||||||||||||||||||||||
| Species Synonyms: | none | ||||||||||||||||||||||||||
| Common Names: | whorled milkweed eastern whorled milkweed |
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| 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 | ||||||||||||||||||||||||||
| Associated species: | Artemisia ludoviciana ssp. ludoviciana, Juniperus horizontalis, Pascopyrum smithii, Schizachyrium scoparium var. scoparium | ||||||||||||||||||||||||||
| RARITY STATUS | |||||||||||||||||||||||||||
| Provincial
Status According to Harms (2003): |
Endangered |
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| Nature Conservancy Status: | G5 S1 |
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| Saskatchewan
Species at Risk Status: |
None |
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| COSEWIC Status: | None |
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| Asclepias verticillata is endangered in Saskatchewan because it is extremely rare in the province. In addition to this species being locally sparse, there are only two known populations in Saskatchewan. Threats facing A. verticillata 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 A. verticillata 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: Buchloe dactyloides and 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: | taproots thin, secondary roots many | ||||||||||||||||||||||||||
| Stems: | perennial, tufted, thin, to 0.5 cm wide glabrous, milky latex | ||||||||||||||||||||||||||
| Leaves: | whorled (3-6), sessile, linear, 3-7 cm long, 1-2 mm wide, abaxial surface lightly tomentulose especially along margin, midrib prominent and white, adaxial surface glabrous, margin revolute | ||||||||||||||||||||||||||
| Inflorescence: | umbels several, axillary or terminal, 8 – 10-flowered; involucre small; pedicels tomentulose | ||||||||||||||||||||||||||
| Flowers: | 5-merous; calyx greenish, reflexed at maturity; corolla yellowish, reflexed at maturity; corona hood white, alternate to corolla lobes, broadly ovate, barely equalling anthers; horn falcate, incurved, protruding from corona hood; gynostegium (adnation of the anthers and the stigma) present; ovary apocarpous but adnate with the style and stigma | ||||||||||||||||||||||||||
| Fruits: | follicles erect, up to 12 cm long, without protuberances; seeds numerous, flattened, silky-comose | ||||||||||||||||||||||||||
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