Taxonomic Study On Indigofera

The genus Indigofera L.,which comprised ca.700 species,belongs to Leguminosae, Papilionoideae.Indigofera was mainly distributed in Tropical Africa.Chinese Indigofera, which comprised 81 species and eight varieties,was previously divided into three subgenera and 14 subsections by Fang.Y.Y & Zheng C.Z.They are mainly distributed in Yunnan,Guizhou,Shichuan,Guangdong.Based on our literature survey,extensive field work and specimen examinations,the the taxonomical significances of the morphological characters were evaluated.Two taxa were used for karyotype studies and 33 samples were used for SEM observation.The main results are summarized as follows:1.Having checked the related specimens,we quantitatively analyzed the morphological characters in relation to I.pseudotinctoria groups and I.pendula groups, and thus evaluated the taxonomical values in their taxonomy.We found habit,twig hairs, leaf shape,phyllotaxis,pod shape,seed number could be used to distinguish subsection or series.For the taxonomy in species level,we found,the number of leaves,petiole length, leaves length,peduncle length,ect.could be applied,while the characters including twig shape and corolla color can be limitedly used in a few cases,and flower number,shape of calyx tooth,calyx tooth longer or shorter than calyx tube have little value in the classification of the genus.2.Under the light microscope(LM) and the scanning electron microscope(SEM), we observed the macromorphology of seeds and the micromorphology of the seed-coat in 31 species and two varieties belonging to 2 genera(Subgen.Indigofera and Subgen. Sphaeridiophora) of Indigofera.The seed shapes could be divided into circular,ne. circular,tr.br.elliptical,tr.Elliptical,quadrate,ne.quadrate,tr.br.oblong,tr.oblong,br. oblong,and the shape of the hilum could be divided into ovate,cordate,elliptical,obovate, obcordate,rhombic,and fusiform.Under SEM,we found variation among the species and five types in the surface pattern of the seeds,i.e.,double reticulum,foveate-reticulate, striate-reticulate,plaque,verruciform protuberances.Under SEM the surface pattern of the seeds shows some variation among the species and five types have been observed,i.e., double reticulum,foveate-reticulate,striate-reticulate,plaque,verruciform protuberances. We analyzed the relationship among these subgerera,within and between sections were discussed based on the seed-coat micromorphology,and supported the viewpoint that Subg. Sphaeridoiphora could be moved into Subg.Indigofera;Seed-coat micromorphological features also suggested close relationships between the species of Subsect.Decorae and parts of Subsect.Pendulae,and among Subsect.Bracteatae,Subsect.Henryanae,Subsect. Squamatae,Subsect.Chaetodontae,Subsect.Hancockian,Subsect.Pseudotinctoriae, Subsect.Scabridae,and parts of Subsect.Pendulae.However,we found no support for the recognition of the 14 subsection of Indigofera proposed by Fang Y.Y & Zheng C.Z. Seed_coat micromorphological features seemed to be quite constant within species and thus are of significant value in the delimitation of some species.Evidence from seed_coat micromorphological features supports the treatment of reducing I.pseudotinctoria and I. hosieii to I.bungeana and the view point that I.emarginata and I.souliei are independent species.The evolutionary trend of the seed_coat micromorphologica features in the genus Indigofera is also Briefly speculated.3.The karyotypes of I.pseudotinctoria was reported for the first time,and its karyotype formula follows 2 n=16=14 m+ 2 sm,being 2A type.The chromosome number and karyotype of I.amblyantha were reported here for the first time,its karyotype formula follows 2 n=16=12 m+ 4 sm,with the karyotype belonging to 2B type.Finally,the variation of chromosome number and evolutional tendency of karyotype were also discussed.From their karyotype,I.amblyantha is in higher evolution level than I. pseudotinctoria. 4.Based on previous literatures and specimen examinations,the characters in relation to the identification of I.pseudotinctoria,I.trfoliata were determined and quantitatively analyses, the taxonomic signification of these characters was also assessed,finally these taxa were taxonomically revised.Our statistic analyses on petal length,calyx length and pod length showed no prominent differences existing among I.pseudotinctoria,I.hosieii and I.bungeana.High variation between or within species of the genus was found in the hairs on the facial leaf, glands on dorsal leaf,leaf apex,leaf shape and pod shape(edges and corners present or absent) between I.glandulifera and I.trfoliata.Thus,I.pseudotinctoria and I.hosieii could be reduced to I.bungeana,and I.glandulifera to I.trfoliata,and I.sylveatrii was reduced as a variety of I.bungeana.5.Based on the 24 characters,the dendrogram of the 63 Chinese species of the genus Indigofera was conducted by using a method of cluster analysis with a software PC-ORD 4.0,to probe into the taxonomical system of the genus.The results show these 63 species of the genus Indigofera could be divided into seven groups:A including Subsect. Henryanae,Subsect.Squamatae,Subsect.Chaetodontae,Subsect.Hancockian,Subsect. Indigofera,Subsect.Pseudotinctoriae,Subsect.Scabridae,B including Subsect.Pendulae, Subsect.Decorae and Subsect.Bracteatae,C including I.bracteata,I.wilsonii and I. hirsuta,D including I.sylveatrii,E includes Subsect.Alternifoliolae,F including Subsect. Trfoliatae and Subsect.Simplicifoliae,and G including Subgen.Sphaeridiophora.Our numerical taxonomy supported the treatment of reducing I.pseudotinctoria and I.hosieii to I.bungeana and inclusion of Subg.Sphaeridoiphora in Subg.Indigofera.