The big white flowers of oenothera caespitosa
, a perennial species, grow from a stemless rosette of long, thin, lobed leaves, which often have reddish stalks. Leaves and stems are covered by short hairs, sometimes glandular. Leaf edges are irregularly lobed, or toothed.
Flowers measure 3 inches or more in diameter, with four pure white petals (deeply notched at the tip), eight pale green filaments topped by broad yellow anthers, and a longer ovarial tube at the center. When mature the petals become light pink, then darker pink or purple when shriveled. Flower buds point upwards and the stems do not have peeling bark, unlike the similar oenothera californica
. The plant is common across all the western states, and inhabits a variety of habitats. There are five varieties, some also quite widespread.