We established microcosms of crop species (Borago officinalis, Brassica oleracea, Glycine max, Lactuca sativa, Lycopersicon esculentum, Ocimum basilicum, Tagetes patula, Zinnia violacea) in a richness gradient from 1 to 8 species to determine the effects of initial richness on the richness and composition of. weed. communities emerging from artificial seed banks. Most crop species performed better in mixture than in monoculture. The richness of . weeds. was not significantly related to the initial diversity of crops, but weed richness did appear to be a function of crop species (even after accounting for variation in crop and weed biomass). The composition of weeds was significantly related to initial crop composition, although not to interactions between crop species.