Studies in Garcinia, dioecious tropical forest trees: agamospermy

In Garcinia, agamospermy is known or suspected for ten species. Most are facultative agamosperms, with males occurring, but males are probably lacking in G. mangostana. In G. mangostana and G. hombroniana, adventitious embryony occurs autonomously, and haploid parthenogenesis may also occur rarely. In G. parvifolia, it is reported previously that gametophytic agamospermy occurs, and adventitious embryos are suppressed. Autonomous endospermy is found in G. mangostana and G. parvifolia. In G. hombroniana, endosperm probably only develops after PEN fertilization. In G. hombroniana, some proembryos are formed precociously, and further proembryo formation is inhibited by sexual embryos. Asexual proembryos tend to occur in large ovules in small ovaries, and sexual embryos tend to occur in small ovules in large ovaries. It is considered that facultative agamospermy renders the genus Garcinia particularly suitable for the development of new types of fruit. Agamospermy in a dioecious genus, adventitious embryony in the absence of fertilization and/or pseudogamy, and the co-occurrence of gametophytic and sporophytic agamospermies in the same genus are unusual phenomena, which are discussed in the context of the lifestyle of a tropical forest tree. For G. hombroniana, n = 24, and for G. cowa, n = 26 are reported.