Patterns of seed germination in Californian serpentine grassland species.

Germination of nine Californian serpentine annual species and one perennial grass was examined as a function of soil and litter cover and seasonal timing of rainfall. Germination responses varied with the date of moisture application, and the patterns of variation differed among species. Germination occurred in waves over time, but in most of the species, virtually all the seeds had germinated by December. These results indicate that yearly climatic variation can affect species composition and competitive relationships among species through the germination process. Soil and litter cover produced little or no effect except for the smallest-seeded species.