yellow starthistle USDA PLANTS SYMBOL: CESO3
Centaurea solstitialis L.
Synonym(s): yellow star thistle, yellow star-thistle, golden starthistle, yellow cockspur, St. Barnaby's thistle

Yellow starthistle is an annual that can grow from ¼ - 3 ft. (0.1-1 m) in height. Leaves near the base are petiolate, dissected, 2-6 in. (5-15 cm) long and usually absent at time of flowering. Leaves further up the stem are decurrent, entire and 0.4-4 in. (1-10 cm) long. Flowering occurs from June to October, when yellow flowers appear in heads at the tips of the branches. Bracts that subtend the flower head have a small cluster of spines and a stout central spine 0.4-1 in. (10-25mm) in length. Yellow starthistle was accidentally introduced into the United States in the mid- 1800’s as contaminate of alfalfa seed. Yellow starthistle invades woodlands, pastures, roadsides and fields.

Identification, Biology, Control and Management Resources