Abstract
Novel, specialized systems exploiting bibionid flies, oil-collecting bees, wasps, or crepuscular settling moths as pollen vectors are added to the range of recorded pollination mechanisms in sub-Saharan Africa Iridaceae, while knowledge of the pollination of previously understudied genera such as Aristea, Bahiana, Ferraria, Hesperantha, and Tritoniopsis is expanded. The pollination of 357 species of the sub-Saharan African Iridaceae now includes 17 discrete systems. Based on repetitive interlinked suites of floral attractants and rewards we now infer pollination mechanisms for an additional 883 species. Many pollination systems recur in genera containing > 10 species. The ancestral pollination in African Iridaceae, and also the most common one, involves large, long-tongued bees that contact anthers or stigmas passively while foraging for nectar. Some 182 species (in 11 genera) lack nectar or oil and pollinators forage preferentially for pollen. Our earlier hypothesis that the diversity of pollination mechanisms within a lineage increases via adaptive radiation and/or character displacement involving simple shifts in floral presentation is expanded to include the role of phylogenetic constraint. Specifically, possession of the meranthium flower in Moraea (ca. 195 spp.) and Ferraria (ca. 14 spp.) of subfamily Iridoideae limits the number of pollination shifts in these genera. More pollination shifts occur in subfamily Crocoideae (ca. 1000 spp.) because the ancestral flower includes tepals united basally into a floral tube and bilateral symmetry. With 16 derived pollination mechanisms described for this family in sub-Saharan Africa it is obvious that phylogenetic constraint is sufficiently flexible to explain the shifts in pollination mode.
Highlights
Iridaceae include some 37 genera and 1190 species in sub-Saharan Africa
The floral biology of 357 species of the sub-Saharan African Iridaceae was examined in situ and in appropriate laboratories in South Africa and North America over a period of 16 years
Bee pollination.-ln our previous review (Bernhardt and Goldblatt 2000) we noted that 14 genera of African Iridaceae contain one or more species pollinated primarily by bees
Summary
Iridaceae (est. 65 genera, 1890 species) include some 37 genera and 1190 species in sub-Saharan Africa. In a previous review of pollination in the family we related these floral characters to suites of morphological and biochemical modes of floral presentation representing five broadly defined pollination syndromes occurring in 21 genera of temperate, winter dry, or Mediterranean habitats (Bernhardt and Goldblatt 2000). These five syndromes (sensu Faegri and van der Pijll971). Continued fieldwork on the native genera indicates that some modes of floral presentation reflect both parallel and convergent evolution in which only a few species or closely related insects or birds remain the primary pollinators of an expanding diversity of co-blooming plant species. Wasp pollination must be added to the list of novel syndromes
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