Plumeless Thistle

Carduus acanthoides

Family: Asteraceae

Description and Life Cycle:

An annual, winter annual, or biennial spread by seeds. Plants are 20-150 cm tall, generally smooth or with scattered hairs on stems and leaves. The upper stem is branched, with spiny wings extending to the flower heads. Mature plants have a well-developed basal rosette of narrow, oblong to elliptic leaves, deeply lobed; the lobes have one to three points, with each point ending in a spine. Solitary flower heads, 1.2-1.6 cm in diameter, form at the end of stems or in clusters on young branches. Flowers are usually purple, but some are white or cream coloured. Seeds are 2.5-3 mm long, and light brown at maturity.

British Columbia Biological Control Agents

• Larinus planus - Beetle (weevil)
• Rhinocyllus conicus - Beetle (weevil)
• Trichosirocalus horridus - Beetle (weevil)
• Urophora solstitialis - Fly

References

Cranston, R., D. Ralph and B. Wikeem. 2005. Field guide to noxious and other selected weeds of British Columbia. Gov. of BC. 94 p.

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.