Northern Prairie Wildlife Research Center
A species absent only from the south central part of North Dakota, spreadpod rock cress occupies large areas to the north, east, and west of our state.
Spreadpod rock cress is a taprooted biennial, fruiting and dying in the second growing season. Mature plants have a basal cluster or "rosette" of withered leaves from the previous season at the base of the stem. The light-green leaves become progressively shorter, narrower, and farther apart on the upper part of the stem. One to three dozen whitish-yellow to pinkish-purple flowers crowd the tip of the plant. The dark, thin pods, which spread outward at maturity, are one to two inches long. Look for spreadpod rock cress on dry, gravelly soils in lightly or moderately grazed prairies.
The rock cresses are members of the mustard family (Brassicaceae), which has been developed into hundreds of ornamentals, and food plants such as cauliflower, cress, radish, kohlrabi, turnip, and rutabaga. Brassica is the Latin name of the cabbage. For unknown reasons, the Swedish father of modern botany Carl van Linne (Linnaeus) coined the generic name after the country of Arabia. The genus numbers about 100 species in the North Temperate Zone. The specific epithet divaricata means "spreading" in botanical Latin. Long-time professor of botany at the University of Wyoming, Aven Nelson (1859-1952), described the species for science in 1900.