Chromosome Numbers in Compositae. XI. Peruvian Species

Abstract

Chromosome counts are reported for 60 collections of Peruvian Compositae representing 59 species in 31 genera. Most of these are first reports for a taxon concerned, including the genera Ascidiogyne (n - 10), Diplostephium (n - 9), Oriotrophium (n - 9), Achyrocline (n = ca 14), Gynoxys (n = 40), Loricaria (n = ca 14), Monopholis (n - ca 30) and Pappobolus (n - 17). Supernumerary or B chromosomes have been found in Baccharis and Monopholis, and an unusual aneuploid series has been detected in Liabum (x = 9, 12, 14, and ca 18). Chromosome counts for 60 collections of Peruvian Compositae are presented in Table 1. Bud material was collected in the field by Dr. John Wurdack and airmailed to the senior author in Austin, Texas, where the counts were made by the usual squash techniques (Turner & Johnston, 1959). Since most of these collections were from remote areas, it was often several weeks before the fixed material could be mailed. These delays and the high temperatures to which the meiotic material was exposed probably account for the numerous approximate counts reported in this paper. (Label-data on the voucher specimens-deposited TEX, US-give approximate counts, plus or minus 1 or 2 chromosomes; in Table 1 we have listed all such counts as approximations only.) Identifications were made by J. Cuatrecasas except for those of Bidens and Coreopsis (by the late E. E. Sherff), Hypochaeris (by A. L. Cabrera) and Liabum rugosum (by R. Ferreyra); chromosome counts were made by Powell and Turner, either singly or in combination.