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Yellowstone County, Montana
Noxious Weed
Weed Information Contact Department

Yellow Starthistle
(Centaurea solstitialis L.)

Sunflower family - Asteraceae


Yellow Starthistle

Photo from Weeds of the West, revised edition.

Yellow Starthistle Toxic

Yellow Starthistle Rosette

Yellow Starthistle Stem

Yellow Starthistle Leaf

Yellow Starthistle Bloom

Yellow Starthistle Plant

Photos from Montana Weed Control Association


Toxic: To Horses

Growth Habit: Annual, erect, rigid brancing stems.

Leaves: Basal leaves deeply lobed, upper leaves not lobed, small, sharply pointed.

Stem: Rigid, covered with a cottony fiber, to 30" tall, winged structures.

Flower: Yellow, terminal, flower bracts are tipped with straw-colored, 3/4 inch thorn.

Roots: Taproot.

Seeds: Smooth, light-colored, often darker mottled, 1/8 inch long, notched just above base.

Reproduction: Seeds.

Habitat: Rangelands, pastures, vineyards, abandoned croplands, alfalfa and small grain fields and roadsides.

Biological Controls: Seed head fly (Terellia uncinata).

Herbicides: None used in Yellowstone County at this time.

Produced by Wyoming Weed & Pest Council in cooperation with Sandoz Crop Protection Corp.


Video Supplied By Ravalli County Weed District