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| Asclepias syriaca L. | Species Image Gallery (opens in a new window) |
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| TAXONOMY | |||||||||||||||||||||||||||
| Family: | Asclepiadaceae | ||||||||||||||||||||||||||
| Genus: | Asclepias | ||||||||||||||||||||||||||
| Species Synonyms: | Asclepias intermedia Vail Asclepias kansana Vail Asclepias syriaca var. kansana (Vail) Palmer & Steyermark |
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| Common Names: | silkweed broadleaf milkweed common milkweed |
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| DISTRIBUTION | |||||||||||||||||||||||||||
| Canada: | southeastern Saskatchewan - Nova Scotia | ||||||||||||||||||||||||||
| Saskatchewan: | southeastern Saskatchewan; Souris River Valley | ||||||||||||||||||||||||||
| Ecoregion: | Moist Mixed Grassland | ||||||||||||||||||||||||||
| HABITAT | |||||||||||||||||||||||||||
| Saskatchewan: | open riverine woods, clearings, and shrubby banks in river valley flats | ||||||||||||||||||||||||||
| United States: | also in fields and waste places | ||||||||||||||||||||||||||
| 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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| Silkweed is endangered in Saskatchewan because it is extremely rare. There is only one population consisting of approximately 200 plants at the last recorded visit. Threats facing A. syriaca include increased grazing and expanding agricultural tillage (Harms 1989a). In addition, the Rafferty Dam, which was constructed after the last record in the W.P. Fraser Herbarium, may have altered the status of silkweed. It should be noted that this species is found within one mile of other provincial rarities: yellow Indian-grass, white-flowered parsely, and American bittersweet (Harms 1989b). | |||||||||||||||||||||||||||
| SPECIES DESCRIPTION | |||||||||||||||||||||||||||
| Height: | to 2 m | ||||||||||||||||||||||||||
| Roots: | taproots deep | ||||||||||||||||||||||||||
| Stems: | robust, ridged, hairless to densely woolly | ||||||||||||||||||||||||||
| Leaves: | opposite, stalks 10 – 15 mm, blades up to 20 cm long, 4 – 11 cm wide, elliptic to broadly oval, apex long-tapered, base rounded to obtuse, upper surface hairless, lower surface woolly with reddish coloured midvein, margin wavy or entire | ||||||||||||||||||||||||||
| Inflorescence: | umbrella-shaped, spherical, 20 – 30-flowered | ||||||||||||||||||||||||||
| Flowers: | scented for insect pollination; < 1 cm wide, 5-merous; sepals green, reflexed at maturity; petals purplish green, reflexed at maturity; corona hood whitish or purplish, short and blunt with a terminus < 3 mm long; horn protruding from corona hood; anthers and stigma fused; ovary with carpels separate from each other but fused with the style and stigma | ||||||||||||||||||||||||||
| Fruits: | pods with soft, spine-like protuberances; seeds silky-hairy | ||||||||||||||||||||||||||
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