Cirsium muticum (Swamp Thistle) - photos and description






Top most bracts spine tipped, lower bracts not spine tipped



General: Tall biennial thistle with leafy stems, an erect growth habit, branching towards the top.

Flowers: Flower heads few, pink in colour, a flower head was measured at 24 mm diameter. Flower heads terminal on long stems or terminal on axillary peduncles. Involucre white woolly, involucre measured at 20 mm long. Top most bracts spine-tipped, lower bracts not spine tipped. Flower heads subtended by a leafy bract.

Leaves: Leaves alternate, cauline, sessile, we measured a large leaf at 23 cm long by 12 cm wide. Leaves deeply cleft into oblong segments, segments tipped with spines. Underside of leaves lighter green in colour.

Height: Height listed in Budd's Flora to 150 cm tall, we measured plants to 175 cm tall.

Habitat: Moist thickets, marshes and swamps, eastern parklands and boreal forest.

Abundance: This is plant is rare, ranked as an S3 (as of 2021) by the Saskatchewan Conservation Data Centre.

Origin: Native.

How to identify this species of Cirsium: This species can be identified by leaves green on both sides when mature, bracts usually without spiny tips - Budd's Flora.

When and where photographed: Photos taken July 30th, swampy woods, Boreal forest, about 400 km northeast of our home in Regina, SK.