General: Plant much branched from a woody caudex, with a decumbent to erect growth habit, and leafy stems. Stems pubescent.

Flowers: Flowers are bright yellow, solitary from upper leaf axils, have 4 petals and reflexed sepals. The stigma is shallowly divided into 4 lobes and does not grow longer than the anthers (unlike other species of Oenothera found in SK which have a cleft stigma and the stigma is exserted beyond the anthers). We measured flowers to 20 mm in diameter. Flowers have a slight scent.

Leaves: Leaves alternate, linear to linear-oblong to spatulate, with a few teeth or entire. Leaf bottoms pubescent, top of leaves glabrous to pubescent. We measured a leaf at 15 mm long and 5 mm wide.

Height: Height is listed in Budd's Flora to 40 cm. We measured plants to 28 cm tall.

Habitat: Dry hillsides, sandy roadsides.

Abundance: Ranked as common by the SKCDC, uncommon in our experience.

Origin: Native.

Synonym: Listed in some of the field guides we use as Calylophus serrulatus. 

When and where photographed: The above photos were taken on June 20th, on a stony, clay hill top, Buffalo Grass Eco Reserve, 200 km southeast of Regina, and on June 28th on steep prairie hillside, Qu'Appelle Valley, 30 km north of our home in Regina, SK.