Cirsium vulgare (Bull Thistle) - photos and description

Involucre with cobwebby hairs.

Looking down at the top of an unopened flower head showing involucre with cobwebby hairs.

Looking straight down on flower head.

Leaves decurrent on stem.

Leaves continuing down the stem, forming prickly lobed wings.

Upper leaf surface with short stiff bristles.

Lower stem leaf in above photo.

Leaf mid-stem in above photo.

General: Stout-stemmed biennial, erect, with usually 1 stem but occasionally up to 5 stems from the caudex. Stems branching towards the top from the leaf axils. This plant is very spiny/prickly. Stems bristly hairy. Plants just beginning to flower in above photos.

Flowers: Flowers numerous, terminal, solitary, magenta in colour. We measured the length of the calyx and corolla together at 4.5 cm long by 4.5 cm wide (width = out to tips of spines). All bracts of the involucre tipped with long spines, and involucre covered with cobwebby hairs.

Leaves: Leaves alternate, decurrent on stem, continuing down the stem, forming prickly lobed wings (Budd's Flora). Leaves oblanceolate, deeply lobed and very prickly. The lower stem leaf highlighted above was 20 cm long by 7.5 cm wide. Leaves with a white stripe down their centre. Upper leaf surface with short stiff bristles, bottom of leaves are bristly on the central vein. Leaves reduced in size toward the top.

Height: Height listed in Budd's Flora to 150 cm, we measured plants to 115 cm tall.

Habitat: Listed in Budd's Flora as waste places and field borders, we found them in the Cypress Hills on sites of old fires, and in forest where the soil has been disturbed by cattle.

Abundance: Uncommon.

Origin: Introduced.

How to identify this species of Cirsium: Bracts of involucre covered with cobwebby hairs, and all bracts spine-tipped; upper leaf surface with short stiff bristles (Budd's Flora).

When and where photographed: Took the above photos July 18th, mixed forest in the west block Cypress Hills, 425 km southwest of our home in Regina, SK.