Reproductive biology of mixed-species populations of Goodyera (orchidaceae) in northern Michigan

The reproductive biology ofGoodyera oblongifolia, G. repens var.ophioides andG. tesselata is discussed with emphasis on the reproductive isolating mechanisms operating in mixed-species populations. Cytology, phenology and pollination of the above three species were studied. Artificial hybridizations were made of these three species and ofG. pubescens. Results show that within mixed-species populations,G. oblongifolia,G. repens var.ophioides andG. tesselata are not completely isolated reproductively, and hybridization does occur. The deleterious effects of the loss of gametes to interspecific crosses are reduced by seasonal isolation, perennial growth and geitonogamous seed production which is encouraged by self-compatibility and clonal growth. Thus, hybridization in mixed-species populations is apparently kept to levels low enough to allow the species to maintain their identities.