Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Perennial sowthistle, Extension, University of Nevada, Reno, Field Guide

Stem

Up to 6 ft. tall, semi-woody, waxy and lacks hair (glabrous); many stems can arise from each crown; often branched near top; branches arise from leaf axils

Photo of perennial sowthistle patch with yellow flowers

Leaves

Alternate; upper leaves are smaller and fewer than lower leaves; leaf bases clasp the stem; exude white, milky sap when broken
Edges (margins) smooth to deeply lobed and spiny

Flower

Yellow; less than 2 in. wide; base of flower is vase shaped; flower base and stalk usually covered with stiff, sticky hairs

Root

Creeping root system

Other

Grows best in moist, fertile soils; often infests crop fields, gardens, waste areas and ditch banks; known to occur in Washoe and White Pine counties
Perennial; reproduces by seed and roots; seed is wind-dispersed

Control

Tilling and mowing not effective; pulling can be effective, but the entire root must be removed. Preventing seed production is essential for control
Apply 2,4-D, aminopyralid, clopyralid, MCPA, or picloram to actively growing plants before bud stage

Learn more about the author(s)

Heidi Kratsch

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Nevada Noxious Weed Field Guide – Perennial sowthistle