Notes on large plant genera with focus on Astragalus

Among 57 genera having more than 500 species, the genus Astragalus, with a large number of species worldwide, is the first big genus in flowering plants. The species belong to 150 sections in Old World and 93 sections in New World, with 3500 species. In the point of species numbers, the genus is divided into three big groups; Small size, medium size, and big size sections. In the Old World, the species are widely distributed in Asia, Europe, and sparsely in African continents. To understand better the high diversity of the genus, it is necessary to seek the main factors of reproduction system, pollination, seed dormancy, soil seed bank, habitat, and speciation mechanism. In this paper, the author tried to explain the biology of the genus briefly. All diagnostic characters are divided into Morphology, Anatomy, Cytology, Physiology, and Chemistry.