Yellow Starthistle (Centaurea solstitialis L.)

Yellow starthistle is an annual, 2 to 3 feet tall, has rigid branching, winged stems covered with a cottony pubescence. Basal leaves are deeply lobed while upper leaves are entire and sharply pointed. Flower heads are yellow, located singly on ends of branches, and armed with sharp straw-colored without bristles, while fruits from disk flowers are lighter and have a tuft of white bristles.

Yellow starthistle, introduced from Europe, grows on various soil types and is usually introduced on roadsides and waste areas. "Chewing disease" results when horses are forced to ea the yellow starthistle.

A related species, Malta starthistle (C. melitensis L.) is similar to the yellow starthistle except the Malta starthistle has smaller seed heads having spines which are branched at the base. University of Idaho Photo

If you would like more information, email MWCA at acamm@montana.edu with your questions. A weed control expert will be happy to answer your questions.