Canada thistle

Canadan ThistleCanada thistle is a member of the Aster or Sunflower family and wasintroduced from Europe. It is a creeping perennial, which reproduces byseeds and fleshly, horizontal roots. The erect stem is hollow, smoothand slightly hairy, one to five feet tall, simple, and branched at thetop.

The leaves are set close on the stem, slightly clasping, and darkgreen. Leaf shape varies widely from oblong to lance-shaped. Sharpspines are numerous on the outer edges of the leaves and on the branchesand main stem of the plant. The flowers are small and compact; about3/4 inch or less in diameter. Color ranges from light pink torose-purple. The seeds are oblong, flattened, dark brown, andapproximately 1/8 inch long.

Canada thistle emerges in April or May in most parts of Colorado. Itis one of the most widespread, and economically damaging noxious weedsin Colorado. Infestations are found in cultivated fields, riparianareas, pastures, rangeland, forests, lawns and gardens, roadsides, andin waste areas. Because of its seeding habits, vigorous growth, andextensive underground root system, control or eradication is difficult.It is distributed across Colorado from 4,000 to 9,500 feet.

Canada thistle Fact/Information Sheet (PDF) Click Here

canada thistle picture

  

 

canada thistle picture

canada thistle picture

canada thistle picture