Abstract: Taxa of Indigofera decera complex, including I. decora Lindl., I.ichangensis Craib, I. cooperi Craib and I. carlesii Cra-ib, are discriminated from one another by a number of quanti-tative characteristics, such as the lengths of calyx and co-rolla, the number of leaflets per pinna, and the pubescence, shape and texture of the leaflets, etc., all of which yet dis-play more or less a continuous variation pattern. A critical study of the group was therefore made in order to shed light on the correlations of variation pattern among the taxa in que-stion. Quantitative measurements of totally 25 characters upon 130 authenticated herbarium sheets from 9 provinces and one autonomous region were varried out, and the data of mean value obtained through these measurements were carefully checked and compared. Finally 11 characters upon 78 sheets of flowering specimens taxonomically significant were chosen (Table 1) and treated statistically by using methods of pictorialized scatter diagram (Figs.1&2) and histogram (Figs. 3&4). All possible diagramatic combinations have been made for the sake of full interspecific comparison. An analysis of these diagrams indica-tes that the complex is composed of four basically morpholo-gical distinct taxa which are on the whole identical to those of conventional taxonomic identification. Yet these diagrams also show the salient trends of continuous variations within the group; the four species are so closely related to one another that they are by no means strictly separable. So it is better to treat them all as taxa of a single species. A proper taxonomic treatment should include the reduction of the morphologically more distinct and geographically allo-patric species I. carlesii to a subspecific rank of I. decora, and the reductions of the other two taxa——I. ichangensis and I.cooperi to varietal ranks of I. decora subsp. decora. An analy-tical key to the subspecies and varieties of Indigofera decoraLindl. is presented.