Mixed stands of chaparral in California usually contains several species of shrubs growing close to each other so that aerial branches and subterranean roots overlap. There is some evidence that roots are stratified relative to depth. It may be that root stratification promotes sharing of soil moisture resources. The authors examined this possibility by comparing seasonal water use patterns in a mixed stand of chaparral dominated by four species of shrubs: Quercus durata, Heteromeles arbutifolia, Adenostoma fasciculatum, and Rhamnus californica . This study supports the concept that co-occurring shrubs of chaparral in California utilize a different base of soil moisture resources.