“…Most orchids are self-compatible, but the pollination mechanisms favour outcrossing (van der Pijl andDodson 1966, Dressier 1990) The interesting perspective of the Orchidaceae from the floral biology point of view contrasts with the comparatively small number of investigations carried out in such a big family. Although nectar is considered one of the most important rewards, sugar composition has only been identified in some 110species (Daumann 1941, FreyWyssling and H&userman 1960, Percival 1961, Payne 1965, Baskin and Bliss 1969, Jeffrey et al 1970 and, as far as we know, sugar proportions have been investigated in four species (Pais and Chaves das Neves 1980, Gottsberger et al 1984, Pais et al 1986, Freeman et al 1991. On the other hand, it is assumed the existence of floral nectaries, but little information is available on the structure and location of them (cf.…”