Study on the pollen morphology of the genus Rumex in China

Pollen morphology of 15 species in the genus Rumer (Polygonaceae) from China was examined by means of LM, SEM and TEM. Pollen grains are spheroidal, subsperoidal, trieolorate, 4-loxocolporate, pantocolporate (hexacolporate mainly), pantocoplate. The ornamentation of exine is microgranulate-perforate, rugulate under SEM. Sexine is thicker than nexine, nexine and intine are united as a foot-layer-endexine unit. According to the characeristics of aperture and ornamentation of exine, pollen grains of Rumex show a fewer difference than those of Polygonum. But 7 pollen groups are recognized, i.e. R. acetosella-group, R. patientia-group and R. obtusifolius-group. The authors agree with wodehouse^s (1931) explanation about the distribution of apertures, and consider that the characteristics of pollen grains of Rumer may be a transitional type in Polygonaceae.