Eastern Forest Threat Center - Bull Thistle

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Bull thistle

Bull thistle

Loke T. Kok, Virginia Tech, Bugwood.org

Bull Thistle
Cirsium vulgare

Bull thistle is native to Europe, western Asia, and North Africa. It is a widespread weed that can grow in a wide range of environments.

Keywords: Asteraceae, biennial, annual, monocarpic perennial, rosette, taproot, lateral roots, spines, achenes; Common names: common thistle, spear thistle

Distribution Map Distribution Source Image

Threat Description

Bull thistle is a biennial, and sometimes annual or monocarpic perennial. In the juvenile phase, individual plants form a single rosette up to about 3 ft. in diameter with a taproot up to 28 in. long. The taproot does not spread, but develops several smaller lateral roots. Stems have spiny wings and grow 1 to 6 ½ ft. tall, usually with many spreading branches. Bull thistle stem leaves are lance-shaped, 3 to 12 in. long, prickly hairy on the top, and very hairy underneath. Leaf lobes are tipped with stout spines. Flower heads are 1.5 to 2 in. in diameter, 1 to 2 in. long, usually solitary, and clustered at the ends of shoots and branches. Flowers are subtended by narrow, spine-tipped bracts. Fruits are achenes, 1/16 in. long, with a long, hairy plume that is easily detached. Bull thistle can be found in natural areas, but is most troublesome in disturbed areas such as pastures, overgrazed rangelands, recently burned forests, forest clear-cuts, and along roads, ditches, and fences. It is found on dry and wet soils, but is most common on soils with intermediate moisture. Once established, bull thistle out-competes native plant species for space, water, and nutrients.