Abstract: An improved procedure utilizing a cytoplasmic-genetic male sterile system for forming F.sub.1 hybrid cottonseeds (i.e., seeds capable of forming hybrid cotton plants of the first filial generation) is provided which is readily amenable to the determination and maintenance of the desired level of purity in the hybrid cottonseed product. The parent plants required for hybrid formation are each homozygotes (as described) with respect to differing leaf shape configurations (i.e., the male sterile female parent plants have a broad-leafed configuration and the fertility-restoring male parent has a narrow-leafed configuration). The resulting F.sub.1 hybrid cotton plants are heterozygotes with respect to leaf shape phenotype and can be visually differentiated from each parent. Following the F.sub.1 hybrid-forming cross-pollination, at least a portion of the resulting cottonseeds are grown, and the approximate proportion of F.sub.