Starthistle - Centaurea calcitrapa
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Purple starthistle is an annual or biennial with a stout taproot. The
leaves are simple, glabrous to pubescent. The leaf margins vary and can
be pinnatifid, dentate, serrulate or entire. The upper leaves are sessile
and slightly clasping; the lower leaves are short petioled. The flowers,
in heads, are purple to pinkish. The involucre, 10-18 mm high, has bracts
that are spinose ciliate to stoutly spine-tipped. Pappus absent. The fruit
is an achene, compressed or obscurely four-sided.
Purple starthistle can be locally abundant in fields, pastures, and waste
places. A biennial, the plant reproduces primarily by seeds.
Starthistle can rapidly colonize new sites displacing native vegetation,
hence diminishing both the area and the nutrient supply for native species.
Links to more information
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers