Alturas Field Office

Noxious Weeds

Bull Thistle   (Cirsium vulgare)
Sunflower Family (Asteraceae) 

Bull Thistle
Photo courtesy of the California Department of Food and Agriculture Botany Lab

Description:  A biennial with a short, fleshy taproot. The stem is 1 to 6 feet tall, widely spreading and spiny winged. Leaves sparsely and prickly hairy above, cottony below with spines on margins. Lower leaves to 16 inches long. Flowers terminal, solitary to more or less clustered, 1-1/2 to 2 inches wide and dark purple. Phyllaries narrow and spine tipped. Seeds straw colored, 1/8 inch long, striped lengthwise with brown or black, with a protrusion at one end, and tipped with plume-like hairs.

Habitat:  Native to Europe. Found in pastures, roadsides, disturbed areas, edges of dry meadows, and log landings. This aggressive weed can form dense patches and makes revegetation difficult due to size, spines, and rapid spread. Scotch thistle may often be found in patches of bull thistle.

Distribution:  Bull thistle may be found throughout northeastern California anywhere there has been soil distrurbance. It can become quite dense in logged areas which have been overgrazed.

Flowering Period:  July - September

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Noxious Weeds