Resumo

CASTRO-CASTRO, Arturo; VARGAS-AMADO, Georgina; HARKER, Mollie  e  RODRIGUEZ, Aarón. Macromorphologicaland cytogenetic analysis of the genus Cosmos (Asteraceae, Coreopsideae), withan identification key. Bot. sci [online]. 2014, vol.92, n.3, pp.363-388. ISSN 2007-4476.

The genus Cosmosis restricted to the Americas, and Mexico represents its center ofdiversification. Some species have a wide distribution and have beenintensively collected, whereas others, due to their narrow distribution, arepoorly known. This has generated a poor understanding of its morphologicalvariability and infrageneric and interspecific limits, as well as confusion atthe intergeneric level within tribe Coreopsideae. Polyploidy and aneuploidyhave played an important role in the speciation of the group. The ploidy levelvariation can be seen between species, as well as in populations of the samespecies. Macromorphological data are used to support recognition ofintergeneric limits, infrageneric groups, and species. Evidence of chromosomenumber variability and geographic distribution information for Cosmos isalso included. These data are fundamental for the taxonomic understanding ofthe genus. A key for the identiication of all species of Cosmos isprovided.

Palavras-chave : endemism; Mexico; polyploidy; xylopodium.