The Biological Reserve of Grama Dam (RBRG) included an area of 263,8 hectares comprehending the physiognomies of semidecidous montane forests, alluvial forests and semideciduous broadleaved forests.
This is an important Atlantic Forest remaining, located in the municipal district of Descoberto, in the "Zona da Mata" (Forest zone) of Minas Gerais.
The area has six sources which flow into two brooks where the

The family Orchidaceae is represented in RBRG for 27 species curiously distributed in 24 genera (Table 1), just three genera have two species: Epidendrum, Gomesa and Polystachya.
Comparettia coccinea, Huntleya meleagris, Psilochilus modestus, Vanilla cf. gardneri, Warrea warreana and Xylobium variegatum are perhaps the rarer species of Orchidaceae species within the Reserve, all of them known only by one population, the first one is quite reduced. On the other hand, Gomesa recurva has a broad distribution, with big populations spreading from the base until the crown of the trees.
Epidendrum secundum presents just a big population, in a rocky next to a brook. Regarding to the other species of Epidendrum occurring in the Reserve, E. densiflorum, just two individuals distant 20 meters from each other have been observed, hanging over a course of water, in half shade, one epiphytic another rupicolous.
Species such as Eltroplectris janeirensis, Oeceoclades maculata, Prescottia stachyodes, Sauroglossum nitidum, all of them terrestrial, have been observed in shade places in many points of the Reserve, although in the most of the time as isolated individuals or a few close individuals, never forming a big population.
Another taxon that should be point out is Wullschlaegelia aphylla which had just a collecting registered for Minas Gerais, in 1856 (Born et al. 1999), it could be a rare species, little collected as it is little conspicuous or even for being misidentified in the herbariums, due to the similarity to the Burmanniaceae's species. In the Reserve, this species, of saprophytic habit, has been observed in a big population in the ground of the wood, in shade place. We can also point out the first register of Polystachya micrantha for the state, just referred before to the states of São Paulo and Rio Grande do Sul, according to Pabst & Dungs (1975).
It is worth to stand out the occurrence of the species such as Cyrtopodium cardiochilum and Eltroplectris janeirensis, just registered for the state of Minas Gerais and Rio de Janeiro (Pabst & Dungs, 1975; Menezes, 2000); Eurystyles actinosophila with register for the states of Minas Gerais, Rio de Janeiro and São Paulo (Pabst & Dungs, 1975) and another such as Catasetum cernuum, Comparettia coccinea, Encyclia patens, Gomesa recurva and Pleurothallis hypnicola distributed through the states of south and southeast region of Brazil (Pabst & Dungs, 1975, 1977). The geographical distribution of those species has, possibly, a close relation with the Atlantic Forest remaining which appears in those states.