Al Schneider's Rocky Mountains Plant Descriptions

Bull Thistle
Cirsium vulgare
Aster family (Asteraceae)

Introduced from Eurasia and now widely established throughout the region, Bull Thistle is considered a weed in many states. The plant does not withstand cultivation. Leaf hairs make leaves feel rough to touch. The -tipped tend to arch outward more so than in other species of Cirsium.


©2008 Keir Morse

Description

Stout and branched , 1-5' tall. Stems are slightly to densely hairy with spiny wings extending down from base of leaves. Leaves cut, bristly hairy on upper surface and white-woolly on lower surface. Leaves dark green on both upper and lower surface. Flowers comprised of numerous rose-purple with that are -tipped. Seeds small and curved with white fluffy plume.

Field Marks

Large showy rose-purple flowerhead, spiny- stems and short, stiff hairs on top of leaves.

© Al Schneider

A noxious weed is considered to be harmful to the environment or animals. Often a governing body designates plants as noxious.

disc flowers are those in the center of a sunflower or daisy. Not a ray flower.

Bracts are modified leaves associated with a flower.

Involucre is the name given to the circle or spiral collection of bracts around a flower-cluster.

spine -- a stiff, sharp structure formed by the modification of a plant organ that contains vascular tissue. A spine can be formed by a latteral branch, a modified leaf or a thorn.

pinnate -- A compound leaf with two rows of leaflets.

biennial -- a plant which lives for two years, producing a basal rosette of leaves the first year and a full plant, flower, and seed the second year followed by the death of the entire plant at the end of the second year.

floret -- A small flower, as in the small flowers that make up an Asteraceae flower head.

wing -- A maple seed has wings.