Northern Prairie Wildlife Research Center
Another of our late-season wildflowers, racemose rattlesnake-root usually can be found in bloom from mid-August to early September. The plant is most common in northern and eastern North Dakota and is generally distributed throughout the area from Alberta to Quebec southward to Colorado and New Jersey, at elevations under 9,500 ft.
Racemose rattlesnake-root may reach a height of three feet in North Dakota. The plant is perennial from heavy roots. The toothed lower leaves are up to 8 inches long and clasp the stem. Stems are smooth except among the flower heads. Up to 60 drooping flower heads form a raceme on the upper third of the stem. Botanists define a raceme as an elongated axis bearing flowers or flower heads on stalks of about equal length. The half-inch long flower heads are greenish to pinkish-purple and very hairy. Fruits are ribbed achenes bearing copious bristles to aid in transport by wind.
This plant is usually found in low prairie sites. There probably is no forage or other economic value to racemose rattlesnake-root, but several closely related species have been used to cure ulcers, sores, and snakebites.
Racemose rattlesnake-root is a member of the sunflower family (Asteraceae), the largest plant family in North Dakota and most temperate areas. There are about 20 species of Prenanthes worldwide. The generic name stems from the Greek prenes, "drooping," and anthe, "flower." The plant was first described for science in 1803 by the French botanist Andre Michaux. In 1792, he was unsuccessfully proposed by Thomas Jefferson to be Meriwether Lewis' companion on an expedition to explore the vast region west of the Mississippi River.