CHROMOSOME-NUMBERS IN THE GENUS NASSAUVIA (COMPOSITAE-MUTISIEAE)

Meiotic chromosome numbers were determined (n = 11 and ca. 44; x = 11) and observations made for eight species of Nassauvia (Compositae, Mutisieae). The numbers include counts for seven species that have not previously been investigated cytologically: N. axillaris, N. chubutensis, N. glomerulosa, N. lagascae, N. revoluta, and N. uniflora (all with n = 11) and N. aculeata (with n = ca. 44). The results reveal three known chromosomal levels for the genus: n = 11 (2x), n = 22 (4x), and n = ca. 44 (8x). Infraspecific polyploidy in Nassauvia is known in N. magellanica with both n = 11 and 22. The closest generic relatives are Calopappus and Triptilion, but no cytological data are yet available for them. The most closely related genus for which chromosomal data are available is Moscharia with n = 20, which suggests that it and Nassauvia could be based on x = 11 (or perhaps x = 10).