Annals of Botany · 2007 · 162 citations · 57 references
Bilabiate blossoms protect their pollen against pollen-collecting bees and at the same time render their pollination more precisely. The huge diversity of realised forms indicate the high selection pressure towards the bilabiate syndrome. As bees are very inventive, however, bilabiate constructions will not represent the ultimate response to bees.
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Diversity and evolutionary biology of tropical flowers
Choice Reviews Online · 1995 · 913 citations
The plant-book: a portable dictionary of the vascular plants...
Choice Reviews Online · 1998 · 713 citations