The cytogeography of Aster pilosus (Compositae- Asteraceae). II. Survey of the range, with notes on A. depauperatus, A. parviceps and A. porteri.

Chromosome numbers of one or more individuals from 269 collections of Aster pilosus were determined from throughout the range of the species. Two cytotypes were commonly encountered: 4x and 6x (x = 8). In var. pilosus, tetraploids and hexaploids were allopatric for the most part. Hexaploids occurred in the northwestern portion of the species' range. Intervarietal and infravarietal pentaploids encountered came from interface areas. All plants of A. pilosus var. pringlei (including var. demotus) were hexaploid and occurred in the northeastern portion of the range of the species. Only 3 plants were found to have supernumerary chromosomes. Two plants were putative heptaploids. In comparison, diploids have been found in the 3 related species A. porteri, A. depauperatus, and A. parviceps. First reports: A. parviceps, 2n = 16; A. pilosus var. pilosus, 2n = 35 and 2n = 42; A. pilosus var. pringlei, 2n = 48 + 2—8 supernumeraries and 2n = 56; A. pilosus var. priceae, 2n = 32.