E-Flora BC: Electronic Atlas of the Flora of British Columbia

Cirsium scariosum Nutt.
elk thistle
Asteraceae (Aster family)

Introduction to Vascular Plants

© Jim Riley  Email the photographer   (Photo ID #28248)

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Distribution of Cirsium scariosum
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SUBTAXA PRESENT IN BC
Cirsium scariosum var. scariosum

Species Information

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General:
Biennial or perennial herb from a taproot; stems erect, thick, fleshy, ribbed, sparsely hairy, simple or with a few short upper branches, 0.2-1.0 m tall.
Leaves:
Basal leaves egg-shaped to elliptic, entire to nearly entire, stalked; lower stem leaves narrowly egg-shaped, tapering to the base, stalked, shallowly to pinnately lobed, marginally spiny with numerous, slender, yellow spines up to 10 mm long, lobed 1/2 or less the width of the blade, segments lanceolate to deltoid, green and nearly glabrous above, woolly-hairy below; the uppermost leaves narrower, ascending, extending beyond the compact group of heads.
Flowers:
Heads discoid, 5-15, in a terminal cluster or rarely at the ends of the few branches or in the leaf axils; involucres bell-shaped, 2-3 cm tall; involucral bracts without glands, essentially glabrous except for the sparse marginal hairs, outer ones egg-shaped to lanceolate, with a slender 2-4 mm long spine, inner ones unarmed, the tips membranous, often dilated, papery and irregularly-margined; disk flowers white to pink, 18-30 mm long, the tubes 9-13 mm long, the lobes 4-6 mm long.
Fruits:
Achenes 5.5-6.5 mm long, light or dark brown with a narrow, yellow apical band; pappus light yellow, 2-3 cm long, shorter than the corollas by 4-5 mm.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Dry open forests in the montane zone; rare in SE BC, known recently only from Crowsnest Pass and Akamina Creek; E to AB and S to ID, MT, CO and AZ.

Source: The Illustrated Flora of British Columbia

Taxonomic and Nomenclatural Links

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