Psychotria species are one of the most commonly found understory shrubs in the tropics. On the 1500 hectare Barro Colorado Island in Panama, there are 21 species of Psychotria. A majority of these 21 species flower during the rainy season. In the rainy seasons of 2000 and 2001, the reproductive biology of seven psychotrias was studied. Hand-pollinations were done on bagged flowers of Psychotria acuminata, P. chagrensis, P. deflexa, P. emetica, P. hoffmannseggiana, P. horizontalis, and P. ipecacuanha. With the exception of P. hoffmannseggiana, all of these species are distylous. Pollinated flowers were collected, stained, and pollen tubes observed using fluorescence microscopy. Preliminary results suggest that P. chagrensis, P. horizontalis, and P. ipecacuanha have the typical distylous incompatibility system. Both P. acuminata and P. deflexa frequently have self and intramorph pollen tubes that grow to reach the ovary. Psychotria hoffmannseggiana appears to be self-compatible. Insect visitors to flowers of each species were observed. With the exception of P. horizontalis, that was visited by a number of bees, wasps, butterflies, and moths, the other psychotrias were most frequently visited by six bee species. These floral visitors were: Osiris mourei, Osiris sp., Paratetrapedia calcarata, Paratetrapedia sp., Trigona fulviventris, and Trigona pallens. Psychotria chagrensis flowered continuously throughout the rainy season, but the remaining six species each flower for about three weeks spanning late April through August. The flowering phenology and similar small, white floral morphology of these species suggests that their continuous, but shifted flowering times, may allow for maximum flower visits by the same bee species.

Key words: Barro Colorado Island, bees, pollen tubes, pollination, Psychotria, reproductive biology