Northern Prairie Wildlife Research Center
A common prairie plant, yellow evening primrose has been found in nearly every county in North Dakota. The species occurs in greatest abundance in the Great Plains from Saskatchewan to Texas but occasionally is recorded as far east as New England.
Look for yellow evening primrose in dry gravelly soils. The plant stands six to twelve inches tall. Several dozen scaly reddish stems, often quite woody in texture, arise from a much-branched root crown atop long perennial taproots. Leaves are slender and sharply toothed. The flower consists of a long slender tube topped by four yellow petals that open to a width of about a half-inch. Seeds are borne in capsules up to an inch long.
There is likely some forage value in this plant for it generally decreases as grazing intensity increases.
Most groups of plants in the evening primrose family (Onagraceae) have flowers that open in late afternoon or evening for pollination hy night-flying insects, but in yellow evening primrose the flowers are open all day. The word onagra stems from a name used by the Greek philosopher Theophrastus for the fireweeds that are also members of this family. The generic name Calylophus means "maned calyx" in botanical Latin probably in reference to the hairs on the outer flower parts. The specific epithet serrulatus means "finely toothed" in botanical Latin. Yellow evening primrose was first collected for scientific investigation by the eminent English botanist Thomas Nuttall (1786-l859). In 1810-1811, Nuttall visited the Mandan villages in what now is North Dakota.