The Colorado butterfly plant is a member of the evening primrose family and is a short-lived perennial herb with one to several reddish, pubescent stems that are 50–80 centimeters (cm) (2–3 feet) tall. The lower leaves are lance-shaped with smooth or wavy-toothed margins and average 5–15 cm (2–6 inches) long, while those on the stem are smaller and reduced in number. Flowers are arranged in a branched, elongate pattern above the leaves. Only a few flowers are open at any one time and these are located below the rounded buds and above the mature fruits. Individual flowers are 5–14 millimeters (1/4 - 1/2 inches) long with four reddish sepals (modified leaves surrounding the flower) and four white petals that turn pink or red with age. The hard, nutlike fruits are 4-angled and have no stalk. Nonflowering plants consist of a stemless, basal rosette of oblong, hairless leaves 3–18 cm (1–7 inches) long. It is a regional endemic restricted to Laramie and Platte counties in Wyoming, and Larimer, Jefferson, and Weld counties in Colorado. The Colorado butterfly plant is likely extirpated in Nebraska; no plants have been found during surveys of historic known populations in the last few years. Of the known populations of the Colorado butterfly plant, the vast majority occur on private lands managed primarily for agriculture and livestock.