STRUCTURAL-ANALYSIS OF FEMALE AND HERMAPHRODITIC FLOWERS OF A GYNODIOECIOUS TREE, OCOTEA TENERA (LAURACEAE)

The evolution of gynodioecy from hermaphroditism involves modification s of floral structure such that male or female fitness is enhanced in hermaphrodites and females, respectively. We present an analysis of st ructural specialization of flowers of Ocotea tenera, in order to evalu ate gender system evolution in this tropical tree species. Significant morphological and anatomical variation was found between high fruitin g and low or nonfruiting trees. Female flowers were significantly smal ler than hermaphroditic flowers, produced no viable pollen, and made r elatively greater allocation to structures that increase female fitnes s. Hermaphroditic flowers were significantly larger than female flower s, produced copious quantities of pollen, and made relatively greater allocation to male structures. Analyses indicated that changes in allo metries between whole-flower growth and growth of reproductive structu res may have occurred, which enhance function of the flower and plant as a male or female. Efficiency of nutrient allocation for reproductio n is argued to be a factor driving gender system evolution in Ocotea t enera.