XVI International Botanical Congess

Gametophyte morphology of tropical epiphytic ferns may confer an advantage for establishment on islands. Most tropical, epiphytic ferns belong to five families: Hymenophyllaceae (H), Grammitidaceae (G), Vittariaceae (V), Polypodiaceae (P) and Elaphoglossaceae (E). Gametophytes of these families are long-lived and clone-forming. In addition, H, G and V possess dispersible gemmae. Although each of these characteristics increase opportunity for outbreeding, island floras are generally depauperate in epiphytic species lacking gemmae (P&E), but generally enriched in epiphytic species with gemmae (H,G&V). We propose that gametophytic gemmae significantly aid long-distance migration of outbreeding species by facilitating gametophyte interaction when spore dispersal is sparse and by promoting exploitation of available niches.