CHROMOSOME COUNTS IN CLIBADIUM (COMPOSITAE, HELIANTHEAE) FROM LATIN-AMERICA

New meiotic chromosome counts are reported from 86 populations from Me xico to Ecuador of 13 species of Clibadium (Compositae, Heliantheae). These, plus previous reports, yield a total of 120 counts from 20 of t he approximately 39 species recognized in the genus (Arriagada, in pre p.). All counts are n = 16 with a few fragments or B-chromosomes obser ved sporadically in some populations. One population, containing what appear morphologically to be interspecific hybrids between C. mexiae a nd C. microcephalum, showed one tetravalent and fragments. Species in both historical sections (Clibadium and Trixidium, created by Candolle and maintained by Schulz) and from the five sections to be proposed i n a new classification of the genus (Arriagada, in prep.) have now bee n counted. The uniformity of chromosome numbers within Clibadium is co rrelated with observed allopatric distribution of closely related taxa .