Pollen size as related to polyploidy and speciation in the andropogon saccharoides—A. barbinodis complex

Summary

Pollen samples were taken monthy, May through October, from 22 clones of Andropogon saccharoides var. torreyanus, grown under two treatments. The mean sample size for all collections was 35.3 µ and the extreme range was 31.4–38.1 µ. Analysis of variance indicated highly significant differences in pollen size between clones and between sampling dates. In a second analysis no significant difference was found between old plants and transplants.

Over 18,000 pollen grains were measured in a comparative study of pollen size in nine Andropogon taxa. A consistent relationship was found between pollen size and chromosome number for three 2n=60 taxa, five 2n=120 taxa, and one 2n=180 taxon. The difference in pollen size between two 2n=120 chromosome taxa is interpreted as reflecting a difference in the pollen size of the three 2n=60 parent types from which they are assumed to have arisen.