Bull Thistle
Cirsium vulgare
Family: Asteraceae
Description and Life Cycle:
A biennial, spreading by wind-borne seed. It forms a large, flat rosette with a long, fleshy
tap root in the first year, and produces a 0.3-1.5m bolt in the second year. The stems are
spiny winged and slightly woolly. Leaves are alternate, deeply lobed, with each lobe ending
in a long sharp spine up to 1 cm long. The upper leaf surface is deep green and has sharp prickles,
while the lower surface is white with small white hairs. Purple flower heads, 3.8-7.8 cm in
diameter, occur throughout the summer.
British Columbia Biological Control Agents
References
Powell, G. W., A. Sturko, B. Wikeem and P. Harris. 1994. Field guide to the biological
control of weeds in British Columbia. B.C. Min. For. Res. Prog.
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