Taraxia is a genus in the Onagraceae family, formerly included in Camissonia, with four species found in western North America (especially in California). Leaves are basal and species perennial, growing from a thick taproot and dormant during fall and early winter. The flowers are yellow or white with four petals and are strongly ultraviolet reflective.
Taraxia ovata (Nutt. ex Torr. & A. Gray) Small, syn. Oenothera ovata Nutt. ex Torr. & A. Gra, Camissonia ovata (Nutt. ex Torr. & A. Gray) P.H. Raven, is found in grassy fields not far from the coast (less than 500 m) from Oregon to central California. It grows from a thick taproot which often branches. The basal leaves are in a rosette, ovate to elliptic with short erect hairs, and the flowers are bright yellow. The fruit is cylindric, swollen by seeds, papery. It flowers March to June. Photos taken by Mary Sue Ittner in Mendocino and Sonoma Counties, California and include a photo of the taproot. She doesn't usually seed seeds which are buried and distributed by ants.
Taraxia subacaulis (Pursh) Rydb., syn. Camissonia subacaulis (Pursh) P.H. Raven, Oenothera subacaulis (Pursh) Garrett, is found in wet meadows at 450 to 2600 m in these western states: Washington, Montana, Wyoming, Colorado, Utah, Nevada, and California. Leaves are in a rosette, lanceolate to narrowly elliptic, usually entire, but sometimes irregularly pinnately lobed and glabrous. The fruit is 4-angled, barely swollen by seeds, leathery. It flowers May to July. The images below were taken by Steve Matson May 2003 in Mono County, California and are included here under a Creative Commons Attribution-NonCommercial 3.0 license.
Taraxia tanacetifolia (Pursh) Rydb., syn. Oenothera tanacetifolia Torr. & A. Gray, Camissonia tanacetifolia (Torr. & A. Gray) P.H. Raven, is found in clay soils in open fields and moist slopes in Washington, Idaho, Nevada, and California from 700 to 2500 m. It is often found in large populations. Leaves are deeply pinnately lobed, hairy, and the stigma exceeds the anthers. It flowers May to July. The first two photos were taken by Mary Sue Ittner near the Feather River, Plumas County. The next two photos were taken by Gary A. Monroe May 2007 in Sierra County, California and are included here under a Creative Commons Attribution-NonCommercial 3.0 license.