Syn.: Cirsium hookerianum Nutt., Carduus hookerianus (A. Gray) A. Heller, Carduus kelseyi Rydb., Cnicus hookerianus A. Gray
Family: Asteraceae Bercht. et J. Presl
Cirsium hookerianum
Distribution: Limited distribution through northwest of North America. Found in Alberta, British Columbia, Idaho, Montana, Washington and Wyoming.
Ecology: Moist soil, grasslands, forests margins, subalpine and alpine meadows, in elevations from 600 to 2900 m. Blooms from June to September.
Cirsium hookerianum
Description: Biennial herb, usually monocarpic. Stem 20–150 cm tall, from taproot, erect, thick and succulent at the base, simple or short-branched,variably woolly with trichomes or finely arachnoid. Leaves alternate, linear to oblong or lanceolate, 5–25 cm long, 1–8 cm wide, margins shallowly lobed, surface with long, soft, arachnoid hairs; basal leaves up to 30 cm long and 5 cm wide. Flower heads borne in terminal spike of 3 or more heads; heads 3–4 cm high; disc florets creamy white or pinkish; ray florets absent; bracts narrow, spreading, spine-tipped, greenish or purplish, surface densely woolly with septate trichomes to tomentose or arachnoid. Fruit is a dark brown achene, 5–6.5 mm long with pappus, 18–22 mm.
Note: The species name commemorates British botanist William J. Hooker (1785–1865), director of Kew Botanical Garden, who sponsored several botanists/collectors to explore flora of North America.
Cirsium hookerianumCirsium hookerianum
Cirsium hookerianum
Cirsium hookerianum
These images were taken in Canada, Alberta, Waterton Lakes National Park (by Karel Bergmann, July 2013) and Canada, Alberta, Jasper NP, Medicine Lake; Banff NP, Bow Lake (by Alena Vydrová and Vít Grulich, 18. and 20. 7. 2007).