The counts of previous authors are confirmed for 2 species. Chromosome numbers are determined in forms not previously counted: 8 haploid chromosomes in B. tuscaloosae Shull ined., B. rubella (Reut.), and B. grandiflora (Bois), and 16 haploid chromosomes in B. occidentalis Shull ined., B. orientalis Shull ined., and B. bursa-pastoris apetala (Opiz). A parallel is shown between chromosome number and behavior in hybridization.