The genus Macrocarpaea consists of 50-60 species of herbs, shrubs (some epiphytic), and small trees restricted to the neotropics. The majority of its species are distributed in mid- to upper-elevation rain or cloud forests in the Andes. Additional species occur in the mountains of southeastern Brazil, the Guayana Highlands, Central America, and the Greater Antilles. A monographic treatment of the genus based on over 1500 herbarium specimens on loan from over 40 different herbaria has been initiated. Nomenclature problems will be resolved, dozens of new species will be described, and dubious taxa will be confirmed. Macrocarpaea is one of only a few genera among that gentians that have hairy leaves in some species. Scanning electron microscopy studies of indumentum anatomy will be evaluated and presented. Large micromorphological variation can also be found in seed and pollen anatomy, as well as in macromorphological characters. Species level cladistic analyses based on ribosomal 5s-NTS and nuclear ITS (internal transcribed spacer) sequences are presented and will eventually be combined with morphological data. Preliminary molecular data suggests that within the distribution area of the genus, the most ancestral lineages are present in the peripheral regions (i.e. Brazil and the Caribbean), with the Andean species representing more recent and more species-rich radiations.

Key words: biogeography, evolution, Gentianaceae, Macrocarpaea, molecular systematics, morphology