Lasthenia conjugens, commonly known as Contra Costa goldfields, is an endangered species of wildflower endemic to a limited range within the San Francisco Bay Area of the state of California, USA.

[4] This annual herb typically flowers from March through June, and its colonies grow in vernal pool habitats at elevations not exceeding 100 meters above sea level.

The Jepson Manual notes that the present distribution is limited to the deltaic Sacramento Valley, principally Napa and Solano Counties,[5] but the historic range of L. conjugens[4] is known to be significantly wider.

Inflorescences appear in the form of solitary heads, with twelve to eighteen phyllaries fused at one third to less than mid length, a distinguishing hallmark for identification of this species.

Some early findings were that repeated seedings in restoration colonies enhanced the resultant population of Lasthenia conjugens and hence ultimate survival.

[14] In addition to the federal status as an endangered species it gained on June 18, 1997, Lasthenia conjugens is acknowledged and protected under the Solano County Habitat Conservation Plan (HCP).

[15] The Solano County Habitat Conservation Plan encourages corridor preservation among vernal pool habitats, which are essential for this species' survival; in addition the HCP states the importance of recognizing genetic differences amongst various colonies of L. conjugens in order to protect the total species genetic diversity.