Breeding Systems in the Flora of a Tropical Deciduous Forest in Mexico

Abstract

Floral sexuality was characterized for most of the flora (708 species) of a forest reserve at Chamela, Jalisco, and compatibility was determined for a sample of hermaphroditic species. Nine types of floral sexuality were found; the frequency of these types was related to life form and systematics. Monostylous hermaphroditism was typical of epiphytes (96%) and herbs (82%) but less so among vines (68%), shrubs (62%), and trees (54%). Dioecy increased across these groups (4%, 1%, 10%, 14%, and 24%, respectively). Monoecy was concentrated in Euphorbiaceae and Cucurbitacea; Boraginaceae and Rubiaceae predominated among the few distylous species. Contrasting vegetation types had similar frequencies of sexuality types. Compatibility tests showed reduced fruiting from self-compared to cross-pollination in 94 percent of 33 species from 14 families, and 76 percent were considered self-incompatible. Intraspecific variation was not salient, but in some cases congeners were notably divergent.