Annals of Botany

Variation and evolution of herkogamy in Exochaenium

Variation and evolution of herkogamy in Exochaenium
Variation and evolution of herkogamy in Exochaenium

The spatial separation of stigmas and anthers (herkogamy) functions to reduce self-pollination and avoid interference between pollen dispersal and receipt. Little is known about the evolutionary relationships among the main forms of herkogamy. Kissling and Barrett examine those relationships in Exochaenium, a genus of African herbs, using phylogeny reconstruction. They find that distyly originated once from an ancestor with approach herkogamy, supporting a theoretical model proposed by Lloyd and Webb in 1992. The results demonstrate the lability of sex-organ deployment and implicate pollinators, or their absence, as playing an important role in driving transitions among herkogamic and non-herkogamic conditions.

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