Tansy-leaved evening -primrose from along the Long Hollow Pass Road about one and one-half miles west of the pass, Steens Mountain, Harney County, Oregon........June 31, 2012.
Tansy-leaved evening-primrose is an attractive, medium-sized and weed-like wildflower. The herbage varies from a dense covering of small, coarse, stiff hairs to covered with appressed hairs or sometimes nearly glabrous. Its leaves are largely basal. They are narrowly to broadly lanceolate to oblanceolate, deeply sinuate-pinnatifid, and range from 5 to 20 cm long and 10 to 35 mm wide. The petioles narrow gradually to the base, and are from one-half to as long as the leaf blade.
The flowers are bright yellow, sometimes aging to purple. They are found in the axils of the leaves and are adapted from cross-pollination. They are rounded in shape and 10 to 16 mm long. The sepals are separately reflexed sharply downward and range from 6-13 mm long. The floral tube is 3-7 mm long while the style is exserted 5-13 mm above the floral tube. The stigma is sublobose or broadly and shallowly 4-lobed. The stamens are unequal in length, with the longest about half the length of the petals. The capsule is sessile, lanceolate-fusiform in shape and widest below the middle. The capsule varies from 1-2.5 cm long and 3-4.5 mm wide.
Tansy-leaved Evening-primrose is found in moist soil in meadows, swales, riverbanks, and alongside roads from riverbanks to sagebrush plains and ponderosa pine forests.
Tansy-leaved Evening-primrose is found from Washington south along the eastern edge of the Cascades to the Sierra Nevada of California, and eastward to Idaho and Montana.
Tansy-leaved evening primrose as seen along the Steens Mountain North Loop Road about one mile downhill from the upper limit of the juniper forest along the road........June 2, 2012.
Tansy-leaved evening -primrose from along the North Loop Road about one-half mile south of the Kiger Gorge Overlook, Steens Mountain, Harney County, Oregon.........August 31, 2011.