Beyond wind: a systematic review of pollination modes in Cyperaceae

Insect pollination has been important in angiosperm diversification, but alternative reproductive strategies also occur. Wind pollination is widespread in Cyperaceae, Juncaceae, and Poaceae; however, ambophily or strict entomophily may have evolved secondarily in some lineages. We conducted a systematic review to synthesize historical evidence of biotic pollination in Cyperaceae and mapped the phylogenetic distribution of genera with confirmed or putative ambophily. We also propose a theoretical gradient of floral attributes to infer pollination modes in the family. Direct evidence of biotic pollination (from field experiments) is documented in three genera (Cyperus, Eleocharis, and Rhynchospora) and indirect evidence, based mainly on floral visitor records, occurs in 10 genera: Bolboschoenus, Carex, Diplasia, Eleocharis, Ficinia, Hypolytrum, Krenakia, Lagenocarpus, Mapania, and Schoenoplectiella. One case of hydrophily is known in Eleocharis. Species with putative biotic pollination are mostly tropical, and ambophily appears to have evolved independently at least 12 times. A trait gradient seems to span from strictly anemophilous species with inconspicuous, widely spaced spikelets to entomophilous taxa with compact, colourful inflorescences and pollenkitt production, with ambophilous forms in intermediate zones. Thus, Cyperaceae provide a valuable model for research on reproductive evolution.