Plains evening primrose (Camissonia contorta), a species of evening primrose, is a native annual found in British Columbia, California, Oregon, Washington, Nevada and Idaho. It grows in a variety of habitats including sandy soils, dry slopes, disturbed areas, grasslands and chaparral.
The plains evening primrose stem arises from a slender taproot. The stem is thin, erect to spreading and bending or curling in aspect, growing 1 to 12 inches in length.
The leaves of plains evening primrose are linear to very narrowly oval, minutely serrated, and form along the stem, not at the base of the plant.
The small, flowers occur singly or in small groups of several flowers. Plains evening primrose flowers have a short red stalk, 4 reddish-yellow sepals and 4 bright yellow petals, which may have red spots at the base and that fade red with age. There is one style and 4 stamens which protrude from the center of the flower.
The fruit of plains evening primrose is a long, narrow, cylindrical capsule containing shiny seeds.
Plains evening primrose leaves and stems may be covered in sparse hairs. The leaves, stems and fruits, particularly in unshaded environments, are often red.
In Canada plains evening primrose is considered a threatened species.
A synonym for C contorta is Oenothera contorta. The genus name, Camissonia, is from the Latin “campestre” meaning “from the fields or open plains”. The bending stem gives plains evening primrose its species name. The Latin for “twisted” is “contorta”.
These specimens were photographed in May along the Lower Hat Creek Trail (Shasta County CA) or in one of our pastures near Lookout CA (Modoc County CA).