Meiosis and Pollen Stainability in Switchgrass, Panicum virgatum L1

Chromosome number, meiotic behavior, and pollen stainability were studied in switchgrass plants originating mainly in Kansas and Oklahoma. Tall, coarse, glabrous plants, referred to as “lowland”, were tetraploid (2n =36). Shorter, finer plants, featuring varying amounts of leaf blade pubescence and referred to as “upland,” were mostly octoploid. One upland plant was hexaploid, however, and four were aneuploid near the 72‐chromosome level. Tetraploids were more regular meiotically and exhibited a higher frequency of well‐stained pollen than either octoploids or aneuploids. Octoploids and aneuploids were similar in meiotic behavior, but the former exhibited a higher frequency of well‐stained pollen. Genetic distinctness of upland and lowland populations was suggested. Asexual reproduction seemed unlikely in tetraploids. It appeared more likely at higher levels of polyploidy where extreme meiotic irregularity suggested materially reduced sexual fertility in occasional plants.