thistle

Weedy species of , , , , and other plant genera of the aster family (Asteraceae). The term usually refers to prickly leaved species of and , which have dense heads of small, usually pink or purple flowers. Because they have spiny stems and flower heads without ray flowers, species are called plumeless thistles. Canadian thistle () is an attractive but troublesome weed in agricultural areas of North America. The thistle is the national emblem of Scotland. 1044

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