Sistemas reproductivos en especies de melastomataceae en la gran sabana (Estado Bolívar, Venezuela)

the reproductive biology of 17 species of melastomataceae was studied in the gran sabana plateau (bolívar state, venezuela) by means controlled crossings in the field; the pollen/ovule ratio, the allocation of floral biomass and the natural reproductive efficiency for each species and its relation with the breeding system were estimated. agamospermy (three species (17.7%) and six (35.3%) facultatives) was the reproductive system, followed by selfcompatibility (seven species, 41.2%), and only tococa guianensis was selfincompatible. most of the studied species displayed high pollen/ovule ratio, which does not correspond with agamospermous reproductive systems. floral biomass revealed that the selfincompatible species has the greater androecium/gynoecium biomass ratio, which agrees with the hypothesis of biomass allocation. nevertheless the patterns of biomass allocation in the other reproductive systems did not show clear tendencies. fruit production was highly variable and independent of the reproductive system; however, all selfcompatible species showed low levels of fruit production and the selfincompatible species display high fruit production.