Biologia reprodutiva de Tapirira guianensis Aubl. (Anacardiaceae), uma espécie dióica em mata de galeria do Triângulo Mineiro, Brasil

Abstract

The reproductive biology of a Tapirira guianensis population was studied in Uberlândia, MG. Between September 1997 and April 2000 the phenology was observed for 17 individuals. Floral biology studies involved floral morphology and rewards, anthesis and flower longevity, inflorescence length and number of flowers, flower visitors and pollinators and breeding system. Tapirira guianensis presented massive annual flowering with quick and well synchronized blooming peaks of both male and female individuals. Flowers of both sexes are small (ca. 3mm across) and inconspicuous. Male inflorescences are larger (Mann-Whitney, U = 1769,5; p < 0,001) and bear more flowers (Mann-Whitney, U = 3; p < 0,001) than the female ones. Male flower offer pollen and nectar while female flowers produce only nectar to flower visitors, all insects (41 species), mainly small social bees and flies. Flower opening occurred both during the day and night for flowers of both sexes and female flowers presented greater longevity. Fruit production and maturation after cross pollination (23,5% and 12,1% respectively) were much larger than from apomixis experiments (1,3% and 0,45% respectively) (χ2 0,05,1 = 561,4; p < 0,001 for fruit production; χ2 0,05,1 = 283,8; p < 0,001 for fruit maturation). Synchronous flower opening, greater floral display of male inflorescences and greater longevity of female flowers of T. guianensis probably increased pollination and consequently fruit production and maturation. Low fruit production from apomixis shows the vital role of pollination agents to the reproduction of T. guianensis, a species of widespread distribution and ecological importance.