The photo at right shows the twisted or contorted fruits which give slender evening-primrose its scientific name (contorta). Photographed along Washington State
Road 14 just west of Rock Creek in the Columbia River Gorge.........April
18, 2002.
Slender evening-primrose is a low growing annual with one stem or more commonly branched and sprawling stems ranging from 5-15 cm long. The herbage ranges from spreading-pubescent to glandular-puberulent. The leaves range from linear to linear-lanceolate or linear-oblanceolate with entire to slightly toothed margins. The leaves range from 10-30 mm long. The floral bracts are of similar shape and size.
The inflorescence often contains stalked glands, especially on the capsules. The flowers are sessile or on short pedicels. The four yellow petals range from 2.5-5 mm long with unequally-sized stamens, the longer pair usually nearly twice the length of the shorter pair. The 4 sepals are reflexed in pairs and each measures 2.5-4 mm long. The floral tube is 1.2-2.3 mm long. The capsule is linear in shape, and ranges from 2-3.5 cm long and about 1 mm in width. The capsules may be straight or contorted.Slender evening-primrose may be found in sandy soils along the coast and along river banks and often times may be found growing amongst sagebrush. It is found from the lowlands up to about 1600 meters of elevation.
Slender evening-primrose may be found along the coast from British Columbia south to Baja California and east along the rivers to the Rocky Mountains.
