Anatomical studies of the root of four Sida species, S. rhombifolia, S. alnifolia, S. scabrida and S. rhomboidea, coming under Sida rhombifolia complex (Malvaceae) were carried out and compared. The genus Sida is the botanical source of the controversial Ayurvedic drug ‘Bala’. Nearly five species of Sida including S .alnifolia are used as Bala.After taxonomic confirmation, observed root morphology, root anatomy and powder microscopy of four Sida species as per standard procedures.Roots of all the four species are distinct in their morphology as well as anatomical characters such as pattern of bast fibres and medullary rays.Based on the anatomical characters, a diagnostic key is prepared which can be used as a supporting tool for taxonomic delimitation of the species coming under the S. rhombifolia complex as well as to ascertain the identity of the drug Bala.