The photo above shows stemless evening-primrose as seenon vernally moist swales along Forest Road #30 southwest of the old Cold Springs Guard Station, Ochoco National Forest.........May 27, 2018.
Stemless evening-primrose is a perennial wildflower with stout taproot with a cluster of basal leaves and low flowers. The herbage of the leaves is mostly glabrous although the leaf margins may have some tiny hairs, or with widely scattered, appressed hairs on the surface of the blades. The leaves ascend or spread from the basal rosette and have elliptic to oblanceolate blades which taper to a definite petiole. The blades range from 5-30 cm long and 1.5-5 cm wide. Some leaves may have small, narrow lobes near the base of the blades, but the margins are otherwise entire or lightly toothed.
The numerous flowers are clustered around the center of the basal rosette, arising from the leaf axils. The flowers open in the morning and wilt by the end of the day. The floral tube is 1.5-3 mm long and is subtended by a sterile, pedicel-like neck from 1.5-7 cm long. The 4 sepals are 6-15 mm long, completely separating and reflexed downwards while in flower. The yellow petals 7-15 mm long and about as wide with rounded but torn or notched tips. The 4 filaments are alternately longer and shorter with anthers at their tips from 1-2.5 mm long. The style is exserted from the floral tube 2-7 mm and capped by subglobose stigma which may be broadly but shallowly 4-lobed. The fruit is a sessile capsule from 1.3-2.5 cm long and 5-7 mm wide. In cross-section, the capsule is quadrangular and each valve has an apparent midrib.
Stemless evening-primrose may be found in meadows and seasonally moist open areas from the lowlands to about 2900 meters in elevation in the mountains.
Stemless evening-primrose may be found in central and eastern Washington south through central Oregon to east-central California and then in south-central Nevada, and central Utah.
The photo above shows stemless evening-primrose as seen along Forest Road #4650 east of Dog Fight Corral at the eastern side of Chief Joseph Canyon in the northern Wallowa-Whitman National Forest.........June 26, 2008.
The photo above shows stemless evening-primrose as seen at milepost 8.4 along the Northern Steens Mt. Loop Road in southeastern Oregon.........5/27/2000.