Pollen morphology of species of Bonamia Thouars, Evolvulus L. and Jacquemontia Choisy (Convolvulaceae) occurring in an ecotone region in the municipality of Caetité, Bahia State, Brazil
ABSTRACT The pollen morphology of 17 taxa of Convolvulaceae [Bonamia agrostopolis, Evolvulus (nine species) - Tribe Cresseae), and Jacquemontia (seven species) - Tribe Jacquemontieae)] was described under light microscopy (LM) and scanning electron microscopy (SEM) with the objective of contributing to the palynology and the taxonomy of the group. The pollen material was collected from anthers and/or floral buds of herbarium exsicates, acetolyzed, analyzed quantitative and qualitatively under LM and SEM, described and illustrated. The data presented here on the pollen morphology of the studied Bonamia, Evolvulus and Jacquemontia species, showed that B. agrostopolis has medium, isopolar, microechinate, granulated pollen grains with the 3-colpate apertural type, which is present in the majority of Jacquemontia species studied. On the other hand, Evolvulus species, J. gracillima and J. pentanthos have the same pollen type, characterized by being spheroidal, pantocolpate and microechinate. The other species of Jacquemontia were characterized by the subprolate to prolate-spheroidal shape, and the zonocolpate and microechinate exine in the pollen grains of all species, with granules, perforations, and micro-reticules in some species. We observed a lack of definition of the pollen types that delimit Cresseae and Jacquemontieae since there are palynological affinities between species of the two tribes. The species of Evolvulus form a stenopalynous group; however, the present study presents unpublished palynological descriptions for nine species, contributing to the expansion of pollen data and confirming the eurypalynous character of Convolvulaceae.