Abstract: Based on cultural experiments of two medicinal Astragalus (A. membranaceus (Fish) Bunge.) and A. membranaceus (Fish) Bge. var. mongholicus (Bge) Hsiao), a comparative biological study on their ontogenetic rhythmes and their biological characteristics of the root, stem, leaf, flower and seed was taken in this paper. As a result, some more evidence were provided for establishing A. mongholicus Bunge as an independent species.

Key words: Astragalus membranaous, A. membranaceus, Comparative biology