THINK YOU KNOW THISTLES?

Not all thistles are created equal. There are certain species which are noxious (legally required to control) and other species which may be unsightly yet don't pose a threat to wildlife habitat or livestock. Below are characteristics to look for in identifying the various species of thistle common to Goshen county. Individual plants may not look exactly the same as the environment can impact the appearance of a plant. 
Correct identification is KEY to implementing effective control.
Musk Thistle
State Designated Weed
This is one of the most common thistles in the area.
  1. Dark green, hairless leaves​ with wide, white midrib​
  2. Margins of leaves appear silver or gray
  3. Long, yellow spines on edge of leaf
  4. Mature height 6-8 feet
  5. Rosette leaves appear and feel waxy
  6. Flower heads deep rose, violet, or purple
  7. Dark purple to brown bracts under flower head
  8. Flower heads typically bent at 90 degree angle
Scotch thistle
State Designated Weed
Scotch thistle is also very common in Goshen county.
  1. Biennial, rosette stage best to control
  2. Leaves densely covered with fine hairs​
  3. Fine hairs give blue-grayish appearance
  4. Long, yellow spines on leaf edges
  5. Mature height 10-12 feet tall
  6. Flower heads violet to reddish
  7. Leaves extend onto stem thus appearing "winged"​
Canada thistle
State Designated Weed
Canada thistle rounds out the top 3 most common thistles
  1. Perennial with extensive root system
  2. Typically found in clumps or patches 
  3. Leaves lack petioles
  4. Leaf margins have small spines
  5. Leaves alternate and oblong or lance-shaped
  6. Mature height 3-5 feet tall
  7. Flower heads white to purple
  8. Flower heads small and compact
Look-a-Likes & Non-noxious thistles
Bull thistle 
Pricklepoppy
​Wavyleaf thistle
​Prairie thistle

A thistle by any other name...may not be noxious!

While found in the area, these are not considered noxious in Goshen county. Click on the picture for more info!
​Russian thistle
Links to species profiles courtesy of: Weeds of the West and GCWP. Images courtesy of Weeds of the West,
King County, Klamath County, Wildflowers West, National Park Service, US Dept of Ag, Jenna Meeks