AbstractThe occurrence of self‐incompatibility inAnemopsis californica(Saururaceae) was investigated in populations located in Irvine, California. Selfed and outcrossed pollinations (pollinations between two populations) carried out in 1995 in a natural population demonstrated that seed production for selfed inflorescences was significantly lower than for outcrossed inflorescences. Naturally pollinated inflorescences produced more seeds per inflorescence than artificially selfed individuals, but far fewer than the artificially outcrossed plants. Additional pollinations were performed the following year in a controlled greenhouse environment using plants collected from the experimental field population. Pollination treatments included selfed and outcrossed pollinations, plus an additional intra‐population pollination to investigate the effect of clonal growth on seed production. Results from greenhouse crosses indicated that seed production for the outcrossed individuals was significantly higher than for selfed individuals or individuals used in intra‐populational crosses. No electrophoretic variation was detected within any of the populations used in crosses, and most putative loci were identical across populations. Results from these studies indicate that self‐incompatibility is present inAnemopsis californica, and that populations may consist of clonally replicated individuals with the same incompatibility reaction.