Taxonomic significance of pollen morphology in Neotropical Schefflera (Araliaceae)
Fiaschi, Pedrodos; Santos, Franciscode; Assis R. Westbrook, Edwina; Plunkett, Gregory M.
Plant Diversity and Evolution Volume 128 No. 1-2 (2010), p. 297 - 323
published: Aug 1, 2010
ArtNo. ESP145012871016, Price: 29.00 €
Pollen grains from 43 species of Neotropical Schefflera were studied under light and scanning electron microscopy to search for variation among species and possible agreement with current taxonomic views. The species investigated are characterized mostly by tri-colporate angulaperturate pollen with lalongate endoapertures and a semitectate sexine, with an ornamentation varying from prominently reticulate to perforate with a psilate to rugulate or rugulate-reticulate surface. Some palynological features support the recognition of a well-defined "Didymopanax" group in Neotropical Schefflera, which can be characterized by unique reticulate-heterobrochate ornamentation. Pollen morphology also supports several additional findings, such as a distinct pollen morphology in S. tremula compared to other species of the "Attenuatae" group of "Sciodaphyllum" (e.g., S. attenuata and S. rodriguesiana), and similar planaperturate pollen grains in S. minutiflora and S. sphaerocoma, despite their placement in different infrageneric groups of "Sciodaphyllum". Overall, however, sexine patterns alone are not sufficient to place species in the current, informal, classification system. Pollen shape and size also varied greatly among species, but did not appear to be taxonomically informative.