Morph bias in inflorescences and individual plants reduces opportunities for geitonogamy in a monomorphic enantiostylous species

O_LIEvolution of enantiostyly, a stylar polymorphism characterised by left- or right-handed flowers, is predicted to counter selfing through disassortative pollen movement. However, in monomorphic enantiostyly, both morphs are present on the same individual, and geitonogamy has been proposed to depend on the morph ratio within an individual. C_LIO_LIUsing a monomorphic enantiostylous Didymocarpus podocarpus (Gesneriaceae) endemic to the Eastern Himalayas, we hypothesised that geitonogamous events would be reduced when plants have a biased morph ratio, due to disassortative pollen movement. We first established natural morph ratios and reproductive compatibilities of the morphs. We next examined the role of morph ratios in pollen movement by recording pollinator visitation patterns using visual observations and quantum dots. C_LIO_LIOur results show that inflorescences and individual plants exhibit biased morph ratios, while the population maintains an isoplethic ratio. Pollen transfer was higher between morphs than within morphs, and pollination success in inter-morph treatments was higher than in intra-morph treatments. Finally, inter-morph switches by the pollinator within plants decreased with an increase in morph bias. C_LIO_LIWe show that biased morph ratios within plants, combined with disassortative pollen movement, can limit the occurrence of geitonogamous events, thus acting as a strategy to increase pollination success. C_LI