• Korean Journal of Plant Taxonomy
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• v.49 no.2
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• pp.101-106
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• 2019

A pollen morphological study was conducted using light and scanning electron microscopy involving six species belonging to the subtribe Neoguillauminiinae. Pollen samples from the six species are tricolporate, and the colpi are surrounded by broad margo, with the widest width in the equator, narrower toward the pole, and rounded at the end. Based on the pollen morphology, pollen of the species in the subtribe Neoguillauminiinae were divided into four types: the Neoguillauminia type (T1), the C. collinus type (T2), the C. casuarinoides type (T3) and the C. paucifolius type (T4). The generic divergence between Neoguillauminia and Calycopeplus was supported by the pollen characters of the size, amb and lumina shape. In particular, the traits of rounded shape in the outline of the polar view and circular lumina, which appear only in the pollen grains of N. cleopatra, support the recognition of Neoguillauminia as a monotypic genus. Calycopeplus oligandrus and C. paucifolius had the same reticulate pattern of pollen grains, supporting Forster's hypothesis that these two species are closely related. On the other hand, the close relationship between the morphologically similar C. collinus and C. casuarinoides was not supported by the pollen characters. Within the subtribe there are two equally parsimonious hypotheses regarding the evolution of exine characters. The first consists of two changes of microreticulate through parallel evolution from the primitive reticulate exine, and the second is that the microreticulate pattern is differentiated from the reticulate state and then reversed to reticulate pollen grains.

• Korean Journal of Plant Taxonomy
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• v.43 no.1
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• pp.1-11
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• 2013

Pollen morphology of 20 species of Euphorbioideae and one from Crotonoideae was examined with light, scanning and transmission electron microscopy. The pollen morphology presented here did not support the monophyly of Euphorbioideae, and the unique characters of tribe Stomatocalyceae such as absence of aperture margins, and thick and continuous endexine suggest the exclusion of Stomatocalyceae from Euphorbioideae which is in accordance with previous phylogenetic studies and wood anatomical data. Aforementioned pollen features in this tribe support that it is closely related to Acalyphoideae. Two subtribes of Stomatocalyceae were well recognized in terms of pollen morphology: Hamilcoinae includes species with reticulate or microreticulate exine patterns, and Stomatocalycinae includes those with perforate patterns with small supratectal elements. Three subtribes of Euphorbieae, classified in terms of pollen morphology, were further divided into three different types including perforate in Euphorbiinae, microreticulate in Neoguillauminiinae and reticulate in Anthosteminae, strongly supporting the Webster's subtribal system. Hureae and Hippomaneae, having perforate sculpturing pattern with smooth margo, were similar in pollen morphology. Especially, the presence of small supratectal elements in Hura crepitans pollen suggests the close relationships with Excoecaria species of tribe Hippomaneae. According to the previous studies, unique intine thickness along the aperture margin in Euphorbieae was not reported elsewhere in Euphorbiaceae. However, in this study we found the same intine thickness along the aperture margin in Maprounea brasiliensis and Hura crepitans. We hypothesize that the similar intine thicknesses found in Euphorbieae and above two species are the evidence of close relationships among them.