Nodding Thistle

Carduus nutans

Family: Asteraceae

Description and Life Cycle:

A herbaceous perennial, or occasionally a winter annual, spreading primarily from wind-dispersed seed. It forms a large rosette in the first year, then produces flowering bolts, 0.2-2.4 m tall, with long, fleshy tap roots in the second growth stage. One to seven erect, highly branched stems form; stems have spiny wings except immediately below the flower head. Leaves in the basal rosette are elliptic to lance-shaped, 15-30 cm long, and pinnately lobed, with each lobe ending in a spine. Leaves range from hairless to densely pubescent. Leaves on the stem are similar but smaller, without lobes, and alternate on the stem. Solitary flower heads, 1.5-4.5 cm in diameter, occur at the ends of branches, usually drooping over (hence "nodding" thistle). Flowers are tubular, pink to purple (occasionally white) in colour. Flowering occurs from July to September.

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.