ArticleWilson, Paul S.Pollen presentation theory (PPT) allows for a re?examination of some classic themes in pollination biology. Here, we outline its implications in the context of bee? and bird?adapted species of Penstemon and Keckiella (Scrophulariaceae). PPT models the . . .
ArticlePollen transfer by hummingbirds and bumblebees, and the divergence of pollination modes in PenstemonWilson, Paul S.We compared pollen removal and deposition by hummingbirds and bumblebees visiting bird-syndrome Penstemon barbatus and bee-syndrome P. strictus flowers. One model for evolutionary shifts from bee pollination to bird pollination has assumed that, mostl . . .