Chromosome Studies in Aesculus

Abstract

Chromosome behavior in pollen formation is studied in many types of Aesculus collected in the Arnold Arboretum from trees normally growing in southern states and in Europe. A. hippocastanurn, A. glabra, and A. octandra were quite regular in behavior. A. rubi-cunda and var. briotii, A. octandra var. hybrida, A. harbisonii, A. mutabilis var. induta, and A. mutabilis var. pendulifolia varied in irregularity and appeared to be hybrids, as the systematists believe. A. hippocastanurn var. baumannii, A. glabra vars. buckleyi and leucodermis, A. arguta, A. fiava, A. discolor var. mollis, A. octandra var. discolor, and A. georgiana, although not considered hybrids, appear to be such according to chromosome behavior. A. woerlitzensis, a form of unknown origin, appeared to be a hybrid. The haploid count of most forms seems to be 20, although A. rubi-cunda and var. brioti have 40 chromosomes and are tetraploid.