Fig. 1. Germination of S. nitidum pollen on S. bicolor stigmas and tube growth 24 h after pollination in pistils of S. bicolor genotypes with and without the iap allele. (A) Sorghum nitidum pollen on a stigma of S. bicolor, Iap Iap. Pollen germinated but the pollen tubes seldom grew beyond the stigma branches. (B and C) Sorghum nitidum pollen tubes have grown through the stigma, style, and into the ovary of S. bicolor genotype, iap iap. Scale bars = 1 µm.