Plants have theoretically multiple alternatives for preventing self pollination and consequently the effect of inbreeding, such as sequential flowering, dichogamy and self–incompatibility to name a few. We investigated the reproductive biology of three sequentially flowering (acropetal) endemic orchids from Puerto Rico. Since sequential flowering is present in the studied species and very rarely (1.0%) is there more than one flower open simultaneously on an inflorescence, we hypothesized that the orchids should be self-compatible and show no effect of protandry (dichogamy). We performed hand self—and crosspollinations and evaluated whether the species are self-compatible and whether the receptivity to pollination success (fruit set) is influenced by the age of flowers (protandry). We define protandry as pertaining to a hermaphroditic organism that assumes a functional male condition prior to shifting to a functional female state. We found that all three species are self-incompatible. Furthermore, flower age is important for predicting the likelihood of fruits set. Older flowers (6+ days) are significantly more likely to produce fruits (functional protandry). The multiple mechanisms for preventing self-pollination (sequential flowering, dichogamy and self-incompatibility) that are noted for these species suggest that the historical evolutionary processes for preventing inbreeding may be complex. We hypothesized that because multiple mechanisms are present for preventing self-pollination inbreeding depression is likely to be high.College of Arts and Sciences University of Puerto Rico, Mayagüez