Seed collections ofGaillardia pulchella Foug. from the eastern and coastal parts of Texas were grown, crossed, and the pollen and meiotic behavior of the hybrids examined. Hybrids involving collections made between the Red River and the Brazos River were meiotically regular and 95–100 per cent of the pollen absorbed stain. When three collections south of the Brazos were intercrossed, the hybrids were again normal. When any collections from north of the Brazos were crossed with any races south of this river, meiosis was irregular and the races apparently differ structurally in one chromosome. The coastal collection produces semi-sterile hybrids with both of the inland cytological groups and seems to differ from the south Brazos group in one chromosome pair, and from-the north Brazos group in two chromosomes. One chromosomal difference is associated with 50–75 per cent pollen stainability and two chromosomal differences are associated with 10–30 per cent pollen stainability. The origin of these chromosomal changes is unknown.