Chromosome numbers are reported for 111 species of Compositae from Argentina, Chile, Costa Rica, Guatemala, Mexico, Paraguay, and Peru. These include first reports for 46 taxa, including 3 genera (Kyrsteniopsis K. & R.: N = 10, Eupatoriastrum Greenman: N = 16, and Piptothrix B. L. Robins.: N = ca. 17). The new combination, Decachaeta pyramidalis (B. L. Robins.) Sundberg, Cowan, & Turner, based on Piqueria pyramidalis B. L. Robins. is proposed.
Summary
An investigation of the style base, filament collar, endothecium, and carpopodium was conducted in order to evaluate their utility as generic markers in the tribe Astereae. The distribution of character states for these microcharacters does not correspond to generic (or, in some cases, infrageneric) limits as they are recognized by recent authors. Use of the microcharacters considered here for delimiting genera would necessitate widespread realignments of the genera in the tribe and would obscure relationships amongst species groups.
The two species of Dicraurus Hook. f. (Amaranthaceae) are shown to be more closely related to different species in Iresine L. than they are to one another. In addition, characters used to distinguish Dicraurus are more widespread within Iresine than was formerly thought, necessitating the merger of Dicraurus into Iresine. The two species as placed in Iresine are I. alternifolia S. Wats. and I. leptociada (Hook. f.) Henrickson & Sundberg. Complete descriptions and distribution maps of the two species are included.
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