Palynological characters of Glycyrrhiza,Glycyrrhizopsis,and Meristotropis(Leguminosae),with special reference to their taxonomic significance

The pollen morphology of 11 species of the genus Glycyrrhiza L.with one from each of the genera Glycyrrhizopsis Boiss.& Bal.and Meristotropis Fisch.& C.A.Mey.was investigated by scanning electron microscopy.In pollen morphology,the main differences between Glycyrrhizopsis and Glycyrrhiza are:Glycyrrhizopsis-pollen grains 36.63 × 40.42 μm in size,oblate spheroidal in shape;and Glycyrrhiza-pollen grains 24.47-33.18 × 23.82-31.83 μm in size,prolate spheroidal in shape.Glycyrrhizopsis and Glycyrrhiza should be recognized as two distinct genera based on palynological and morphological characters.Meristotropis and Glycyrrhiza are similar in many important palynological and morphological characters,suggesting that the two should be merged.In Glycyrrhiza,two types of pollen grains,3-lobed-circular or subtriangular in polar view,are found in different species,in accordance with morphological differences in the two groups,shedding light on the classification and evolution of the genus.