Systematics Of Glycyrrhiza L. (Fabaceae)

The genus Glycyrrhiza L. belongs to Fabaceae, Galegeae, Glycyrrhizinae, and is distributed in all the continents. After careful study on the morphology of Glycyrrhiza, with special reference to the scopes of variation within and among populations, the author found that the keels of the genus were not fused together for the first time, which corrected the wrong description in Flora Reipublicae Popularis Sinicae 42 (2), and put forward that the shapes of pods and leaflets were reliable diagnostic characteristics, and that the number of leaflets, the density of inflorescence and the size of flowers were also useful for the delimitation of species within the genus. Pollen grains of thirteen species distributing through Europe, Asia, America and Oceania were investigated by scanning electron microscopy (SEM) for the first time. The pollen grains were prolate spheroidal or oblate spheroidal. The colpi were tricolporate, usually broad, and have an irregular margin. Colpi membranes were granular or verrucate. The most frequent exine sculpture was foveolate, and otherwise perforate and rugulate. The variation in the pollen's shape, size and exine sculpture in the genus provided some taxonomic support for existing classifications. The SEM results to seed sculptures of eleven species representing three sections of Glycyrrhiza indicated that the seed sculptures were no values for taxonomy since they were very similar within genus. The internal transcribed spacers (ITS) of five species in Glycyrrhiza were sequenced, and ITS data of twenty-one species including two species of Glycyrrhiza and ten related genera in Galegeae were downloaded from genbank, and with Wisteria sinensis as outgroup, then Phylogenetic tree was constructed. The result of parsimony analysis strongly suggested that Glycyrrhiza was a monophyletic group. The phylogenetic tree including the tribe Galegeae, Trifolieae, Vicieae, Cicereae, Hedysareae and Tephrosieae illustrated that the genus Glycyrrhiza and other genera in Galegeae were clustered in different clades, which indicated that Glycyrrhiza and the other genera of Galegeae were far related, and the tribe Galegeae was not monophyletic. Further studies were needed to determine the systematic position of Glycyrrhiza in Fabaceae. According to the comprehensive studies by the examination on 4000 herbarium specimens, field observations, palynology, seed morphology and molecular systematics, the taxonomic revision of Glycyrrhiza in the world has been made. Thirteen species and one variety were recognized into three sections: Sect. I. Glycyrrhiza, Sect. II. Pseudoglycyrrhiza. and Sect. III Meristotropis; Seven species and ten varieties or forms were reduced to synonymies, and one new combination was proposed. The scopes of variation in G. uralensis and G. glabra were re-confirmed, and the identities of the two species were clarified. Typification of the species in Glycyrrhiza were checked, the correct name for the plants in G. inflata should be G. paucifoliolata, and a proposal was given to conserve the name G. inflata. The genus Glycyrrhizopsis was separated from Glycyrrhiza, two species and one variety were recognized in this genus, and one new combination was proposed. At last, Descriptions on, distribution maps for and a key to the genus Glycyrrhiza, series and species were also given.