Seed morphology of the genus Astragalus L. from North Asia

Astragalus is one of the largest genera of angiosperms and a characteristic component of the steppes and mountains of North Asia. Here, we used scanning electron microscopy to investigate the seed morphology of 56 species of the genus from North Asia. In Astragalus, seed color varies from yellow-green, greenish brown, reddish brown to grayish brown. Seed shapes include reniform- globose, rombiform, and oblong-elliptical. Seed sizes vary from 1.25 x 0.88 mm to 4.94 x 3.29 mm. Anticlinal walls are straight, undulate, or slightly thickened, and the periclinal walls are aveolate, stellate, pectinate, or rugose. We recognized two main types of seed surface in the genus: reticulate (sect. Cystium, Uliginosi, and Heterodontus) and indistinct primary sculpture (sect. Caprini, Craccina, Alopecuroidei, Glycyphyllos, and Komaroviella). This study describes macro- and micromorphological characters of seeds that would be useful for studying systematics, taxonomy, and evolution within Astragalus in the future.