Appendicular origin and structure of the spur of Vochysiaceae flowers

Abstract

Floral nectaries are linked with animal pollinators and fl oral specialization, characterizing some plant groups, such as the mostly Neotropical Vochysiaceae. Th e phylogeny of these plants has been revised based on molecular data, but their conspicuous spurs were mostly neglected. Th e appendicular or receptacular origin of these spurs has been discussed but without ontogenetic or anatomical study, and the association between spur structure and pollination systems was never assessed. We studied the spurs of species of four genera of Cerrado Vochysiaceae (tribe Vochysieae), documenting their vascularization and comparing their structure to previously described pollination systems. Th e spur structure was roughly similar among species, and vascularization confi rmed their appendicular origin. Subepidermic secretory tissue surrounded the lumen of the spur and nectar was secreted through nectarostomata. Besides diff erences in size and cuticle striation, no other association between spur structure and pollination system was observed. However, the structure is somewhat distinct in Qualea parvifl ora, which sports a pluriseriate internal epidermis padding the spur lumen, which may provide protection against damage by the large bees that visit these relatively small fl owers. Th e conservative histology and vasculature somewhat confi rmed the monophyly of the tribe Vochysieae and the appendicular origin of the spur in the Cerrado Vochysiaceae.

Reproductive biology and pollinators in two enantiostylous Qualea species (Vochysiaceae) in the Brazilian Cerrado

“…In Q. parviflora the petal is violet and in Q. multiflora it is white but opening and cream‐coloured during the receptive day. Flowers have a spur containing nectar and nectar guides on the petal (Shimizu ; Carmo‐Oliveira et al ). Pollen release occurs early in the morning of the second day, even before the flower is completely open (Barbosa ; Santos ).…”