Current Status of the Systematics of Astragalus L. (Fabaceae) with Special Reference to the Himalayan Species in India

Abstract

Astragalus is considered one of the most diverse genera in the family Leguminosae (nom. alt. Fabaceae). Although a large number of works have been carried out on the genus, no monograph is available except some regional accounts and revisions chiefly at sectional level. It may be due to the sheer size of the genus (ca. 3000 spp.) and diverse nature, the genus is quite variable in habit and habitats, size of the plants, nature of indumentums, stipules, leaf rachis, types of inflorescence, relative length of petals, pods etc. Usually, genus is divided into eight to ten subgenera and more than 245 sections. In recently conducted molecular phylogenetic studies it has been shown that none of the subgenera and large sections are monophyletic. However, it has been clearly demonstrated that Astragalus is monophyletic except some outlier species. The chromosome numbers are also quite interesting and significant in Astragalus for its phylogenetic studies. There is a strong correlation between its geographic distribution and chromosome numbers. Currently about 80 species have been recorded from India chiefly from the Himalayas. Except some of our recent publications, not much studies have been carried out on the genus in India after 'The Flora of British India'. Astragalus is not of much economic importance, however, some of its species are well known for commercial gum tragacanth production especially in Iran and China. In India, A. candolleanus is a well known drug as 'Rudanti' or 'Rudravanti' used for tuberculosis, skin diseases, coughs and blood purifier. The aim of this article is to review the entire work carried out on Astragalus and to bring out scattered information at one place for better understanding of the subject and to find out the future prospective of the research in India on the genus.