The photo above shows a close-up of the red-spotted flowers of club-fruited evening-primrose (variety purpurascens) as seen along a dry streambed that feeds into Cottonwood Creek at the informal campground as the creek flows out of the Pueblo Mts of southeastern Oregon.........5/27/2000. Note the long style exserted beyond the stamens from the floral tube with its globose stigma at the tip.
Club-fruited evening-primrose is an annual to winter-annual wildflower with a cluster of basal leaves and erect to spreading stems. The stems may be simple or branched near the base. The central stem is often erect while the side stems may be prostrate to ascending. The herbage varies from mostly glabrous to partly glandular to covered with straight, stiff, sharp and appressed hairs. The leaves ascend or spread from the basal rosette and have lanceolate, lance-ovate, lance-elliptic or broadly ovate blades which taper to a definite petiole. Small, lateral leaf segments may be found below the large terminal blade. The blades range up to 9 cm long and up to 4 cm wide. The margins of the blades are lightly to coarsely toothed. If the latter, the teeth may be regularly toothed, or the teeth may be widely spaced.
The numerous flowers are found in elongated, many-flowered racemes at the terminus of each of the stems. The unopened buds are closely crowded at the ends of the nodding stems (See photo at right.). The floral tube is 3-6 mm long. The 4 sepals are 3-6 mm long, completely separating and reflexed downwards while in flower. The petals are 4-10 mm long and range from yellow to white or creamy. They often have reddish spots near the base of each petal (See photo above.). The 8 stamens are roughly equal in size, their filaments from 2-5 mm long and anthers 2.5-5 mm long. The style is elevated above the anthers at flowering time. The fruit is a thick, cylindrical capsule from 1.2-3 cm long and 1.5-3 mm thick. The capsules are roughly 1-5 times longer than the ascending pedicels, which range from 4-15 mm long. The capsules may also be club-shaped (hence the common name), narrowest at their base, gradually widening to the distal tip.
Subspecies cruciformis: Petals yellow. Flowers generally open in the morning and wilt the same afternoon. The flower opening seldom follows the pattern of variety purpurascens.
Subspecies integrior (formerly Variety purpurascens): Petals white or creamy. Flowers generally open in late afternoon to early evening and wilt the next day.
Club-fruited evening-primrose may be found in open areas in the desert on sandy, gravelly or clay soils in the lowlands and basins up to elevations of 2000 meters.
Club-fruited evening-primrose may be found from southeastern Oregon south (to the east of the Sierra Nevada) through Nevada to southern California and into northern Baja California. It is found east to Owyhee County, Idaho and further to the southeast to southwestern Utah and central and southeastern Arizona.