Members of the Chrysobalanaceae are distinguished by a single pistil with a gynobasic style. The purpose of this study was to examine the floral development of representatives of this family in order to determine how the gynobasic style is formed. The flowers of the two representatives examined, Chrysobalanus icaco and Licania michauxii, also differ in the number of stamens they typically have (12-26 in C. icaco and approximately 15 for L. michauxii). The pattern of stamen development was therefore also examined to determine how this difference in number is achieved. The difference in the number of stamens between the two species was found to be due to two processes: a larger number of stamens being initiated in the inner whorl of C. icaco flowers (typically four opposite each petal as opposed to two opposite each petal) and subsequent suppression of stamens on one side of the C. icaco flowers. Carpel initiation in L. michauxii begins when three carpel primordia become visible during initiation of the antepetalous stamen whorl. The originally distinct carpel primordia become laterally confluent in the portions below the free tips. Later in development the ovaries of two of the carpels are suppressed leaving a single developing ovary. The developing ovary expands outward and upward causing the style, which is apparently composed of tissue from all three carpels, to become gynobasic. Only two carpel primordia are initiated in flowers of C. icaco. Further development of the gynoecium is similar to that found in L. michauxii in that one of the two ovaries is suppressed leaving a single developing ovary with a gynobasic style apparently composed of tissue from both carpels. In conclusion the gynobasic style is produced by a suppression of ovaries in both species, although different numbers of carpels are initiated and suppressed in the two species.

Key words: Chrysobalanaceae, Chrysobalanus icaco, floral development, gynobasic style, Licania michauxii