Flodman's Thistle

Photo by Dr. Rodney G. Lym
Courtesy of North Dakota State University Extension Services

 Flodman's Thistle grows perennially and sometimes biennially from deep roots called taproots; new plants can grow from the horizontal roots.  It grows to be two to three feet tall.  The stems appear blotchy white because of white hairs that become tangled into bunches.  The leaves are about six inches long, though shorter near the top, and are shiny green with a hairy underside.  They are unevenly lobed with a tooth-like appearance on the edges that end with spines.

Photo by Dr. Rodney G. Lym
Courtesy of North Dakota State University Extension Services

The growing season begins in June, with flowering in mid July through September.  The flower heads have overlapping bracts, ending in strong yellow spines.  They excrete a stick substance that attracts and traps insect.  Each plant can bear up to five spiny flower heads.  The tube-shaped flowers range from deep purple to pink and are between one and two inches wide.  There is also a rare white flowering form of Flodman’s Thistle that can sometimes be found in North Dakota.

 
Photo by Dr. Rodney G. Lym Courtesy of North Dakota State University Extension Services

The seeds or achenes are between 0.1 and 0.15 inches long.  They are oval in shape and vary between tan and brown with a prominent yellow collar.  They have a tuft of bristles about an inch long to carry them into the air on windy days.

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