Chromosome Numbers and Satellite Chromosome Morphology in Aster and Lasallea

Chromosome numbers were determined from more than 241 populations of 46 species and five interspecific hybrids of Aster L. (X = 9, 8, 7) and from 48 populations of nine species and one interspecific hybrid of the redefined genus Lasallea Greene (X = 5). Seventeen first reports are listed for Aster and four for Lasallea . The Nucleolar Organizer Region chromosome of the species of Aster examined had a satellite either equal to or longer than the short arm region, while all nine species of Lasallea had a very small satellite. The retention of the species of subg. Oxytripolium (X = 5) in Aster was found questionable on cytological grounds, and it was done so for nomenclatural reasons only.