A floristic survey of the Orchidaceae of the Reserva Ecológica do Guará, a small conservation unit with 194 ha located in the Distrito Federal, central Brazil, is presented. Forty four genera, 100 species, and five subspecific taxa are recorded for the Reserve. The most representative groups are the genus Habenaria (32 taxa), subtribe Spiranthinae (six genera and 14 taxa) and the genus Cyrtopodium (seven species). Of these, 80 (76%) are terrestrials, while 22 (21%) are epiphytic. Forty two taxa occur in forest physiognomies, where they are distributed according to vertical gradient of light and humidity. In grassland physiognomies occur 63 taxa, distributed according horizontal gradient of humidity, ranging from the campo limpo inundável (flooded grassland) to the campo sujo seco (dry shrub) and cerrado. The campo limpo inundável and campo úmido (humid grassland), with 42 taxa, are the physiognomies with the highest number of species. The Reserva Ecológica do Guará, though its small area, is the locality in the cerrado biome with the highest number of orchid taxa. Considering the current knowledge, the Reserva Ecológica do Guará rivals or exceeds in number of taxa other orchid-rich areas in other Brazilian biomes.
Orchidaceae; cerrado; Reserva Ecológica do Guará; Distrito Federal; Brazil
