Northern Prairie Wildlife Research Center
Often simply called "prairie thistle," Flodman's thistle is found throughout North Dakota. Elsewhere, the natural range of the plant is from southern Manitoba to British Columbia south to Iowa and Arizona at elevations up to 9,000 feet. Plants found in the northeastern United States have been introduced.
Flodman's thistle is perennial from a taproot. Young plants can grow from horizontal roots. Stems, which are usually about three feet tall in North Dakota, are covered with wooly hairs that becomes tangled in bunches, giving the stems a mottled white appearance. Basal leaves are about six inches long, the upper much shorter. All are greenish above and gray wooly below, deeply incised, and bear sharp spines. Each plant bears one to five spiny flower heads nearly two inches wide. The numerous disc flowers are a gorgeous purple. The seeds (achenes) are only about an eighth inch long, but bear a tuft of inch-long bristles to carry them aloft during windy days.
Look for Flodman's thistle from July to September around the bases of hills and in coulee bottoms in native prairie pastures. Like many of our prairie plants, this thistle seems to be little affected by grazing intensity in the moister, cooler, eastern part of its range, but does better under light or moderate grazing in the warm, arid west.
Other Cirsiums from Eurasia and North America were used for foods and medicines. Amerindians especially liked to eat the roots and soft, sweet stems, but I found no mention of Flodman's thistle in this regard. This is often the case, because, compared to many other areas in North America, the use of Great Plains plants by native peoples were poorly documented.
Thistles are members of the sunflower family (Asteraceae). Aster means "star" in Greek, in reference to the radiate arrangement of the flowers in the heads. The family contains over 15,000 species, more than any other family in North Dakota as well as nearly every country in the North Temperate Zone. The generic name is derived from the Greek cirsos, "a swollen vein," for which the early European herbalist-physicians thought thistle a remedy. The eminent Swedish-American botanist Per Axel Rydberg (1860-1931) dedicated the specific name in 1896 to the discoverer of the plant, J.H. Flodman. Rydberg curated the collections of the New York Botanical Garden and authored several major North American floras.