Abstract Pollen morphology serves as a valuable tool for taxonomic characterization and evolutionary studies. In this study, we conducted a detailed morphological analysis of pollen grains from 16 species of Machaerium Pers. (Fabaceae) occurring in São Paulo, Brazil. Pollen samples were obtained from herbarium specimens and subjected to both qualitative and quantitative analyses using light microscopy and scanning electron microscopy. Our results confirm the stenopalynous character of Machaerium pollen, characterized by monads, isopolar pollen grains, 3-colporate with narrow colpi, and microreticulate exine. Quantitative measurements of colpus length and width, and endoaperture width, proved to be relevant for species differentiation. Additionally, qualitative characteristics such as pollen size, amb, shape, aperture position, presence of fastigium, and the thickness of the exine layer were identified as distinguishing factors among species. Despite variations observed, our analysis did not reveal distinct pollen features for taxonomic sections within the genus, indicating a high degree of pollen similarity among species. These findings contribute to our understanding of pollen morphology in Machaerium species and highlight the importance of pollen characteristics in taxonomic studies and evolutionary research. study 1 Pers Fabaceae (Fabaceae Paulo Brazil monads 3colporate colporate 3 colpi width differentiation Additionally size amb shape position fastigium observed genus research

ABSTRACT Morphological variations in angiosperm pollen grains may aid in the differentiation of families, genera and species. Sapindaceae pollen morphology holds promise for the recognition of taxa of this cosmopolitan family, which is well distributed in tropical regions and possesses great morphological diversity. This study presents the pollen morphology of 23 native Brazilian species of Sapindaceae from forest fragments in the state of São Paulo, Brazil. The aim was to identify pollen types in order to expand the morphological knowledge of the analyzed species and contribute to the taxonomy and conservation of the family. Pollen grains were acetolysed, measured and photographed using light and scanning electron microscopy. Qualitative data were described for three pollen types, while quantitative data were analyzed by descriptive and multivariate statistics. The pollen grains are monads, isopolar or heteropolar, small to medium in size, peroblate to oblate-spheroidal and with a subcircular to quadrangular amb. Variation in the type of the apertures [3-porate, 3-(4)-colporate, 3-syncolporate or 3-parasyncolporate] allowed the analyzed genera to be separated into three pollen types. Furthermore, differences in ornamentation (psilate, rugulate, striate, microreticulate, reticulate) delimit species within the established pollen types.

No presente estudo foram investigados os grãos de pólen de quatro espécies pertencentes à família Boraginaceae (Cordia sellowiana Cham., Heliotropium indicum L., Tournefortia breviflora DC., T. villosa Salzm. ex DC.) e de duas espécies de Gesneriaceae [Nematanthus villosus (Hanst.) Wiehler, Sinningia allagophylla (Mart.) Wiehler] ocorrentes na "Reserva do Parque Estadual das Fontes do Ipiranga". São apresentadas descrições, ilustrações e observações para todas as espécies estudadas.

Pollen grains of four species of Boraginaceae (Cordia sellowiana Cham., Heliotropium indicum L., Tournefortia breviflora DC., T. villosa Salzm. ex DC.) and of two species of Gesneriaceae [Nematanthus villosus (Hanst.) Wiehler, Sinningia allagophylla (Mart.) Wiehler] occurring in the Reserva do Parque Estadual das Fontes do Ipiranga were examined in the present study. Descriptions, illustrations, and observations of all species studied are presented.