SummaryIn an effort to determine the physical basis of the maternal inheritance of triazine resistance inAmaranthus hybridusL. the fate of plastids and other organelles in developing pollen was investigated in triazine‐resistant and susceptible biotypes. In both types, immediately after microspore mitosis, the newly formed generative cells contained an array of organelles (golgi bodies, endoplasmic reticulum, plastids and mitochondria) similar to that in the larger vegetative cells. No selective exclusion of organelles from the generative cell was noted although only small plastids were present. The immature generative cells contained small vacuoles, within which degenerate organelles were frequently observed, and no ultrastucturally recognizable plastids were found in mature cells. Maternal transmission of the triazine resistance factor thus appears to be due to a selective destruction of paternal plastid