﻿AbstractThe lack of diagnostic taxonomic characteristics in some species complexes leave the species delimitation ofOxytropisDC. unresolved. Seed morphological features have proved to be useful diagnostic and taxonomic characteristics inFabaceae. However, there are few systematic studies on the seed characteristics ofOxytropis. Here, we used scanning electron and stereoscopic microscopy to investigate the seed characteristics of 35 samples obtained from 21Oxytropisspecies from northwest China. Our examination showed two main types of hilum positions, terminal and central, and five different types of seed shapes: prolonged semielliptic, reniform, prolonged reniform, quadratic, and cardiform. Seven different sculpturing patterns were identified: scaled, regulated, lophate with stellated testa cells, simple reticulate, rough, compound reticulate, and lophate with rounded testa cells. The seeds ranged from 1.27 to 2.57 mm in length and from 1.18 to 2.02 mm in width, and the length-to-width ratio ranged from 0.89 to 1.55 mm. The seed shape was constant within species and was useful for species delimitation within the genusOxytropiswhen combined with other macroscopic traits. In contrast, the sculpturing patterns were highly variable at the species level and could not be used for species identification. Results of the cluster analysis and principal component analysis (PCA) indicated that the seed traits ofOxytropisspecies are useful for taxa identification at the species level, but have low taxonomic value at the section level.