Stem

  • Up to 2 ft. tall, highly branched and rough-textured; multiple stems can arise from woody crown; NO wings on upper stems 
Photo of squarrose knapweed stem with leaves

Leaves

  • Exist as a basal rosette prior to bolting; alternate; lower leaves pinnate-divided and 4-8 in. long; sometimes covered with short grayish hairs; upper leaves strap-like (linear) with smooth edges (margins)
Photo of small squarrose knapweed plant

Flower

  • Pink to purple, each located at the tip of a branch; base of flower is narrow vase-shaped, 0.3 in. long, 0.12 in. wide and covered with comb-like bracts; bracts tipped with a spine less than 0.12 in. long that curves outward 
Photo of squarrose knapweed plant with bright pink flower

Root

  • Deep, stout taproot
Photo of squarrose knapweed plant

Other

  • Often infests rangelands, waste areas and roadsides; known to occur in Elko and Humboldt counties 
  • Perennial; reproduces by seed
Photo of squarrose knapweed plant with small pink flowers

Control

  • Mowing plants in bud to flower stage can reduce seed production; repeated hand removal can be effective; DO NOT burn
  • Several insect biological control agents are available
  • Apply 2,4-D, dicamba, or glyphosate in the rosette stage; aminocyclopyrachlor, aminopyralid, clopyralid, or picloram preemergence to mid-bolt stages
Peer Review Logo
Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Squarrose knapweed, Extension, University of Nevada, Reno, Field Guide

Learn more about the author(s)

Heidi Kratsch
Heidi Kratsch
 

Also of Interest: