Seedlings of Achvranthes aspera L., Cassia tara L. and Ruellia tuberosa L. with their radicle and plumule were treated for 72 hours with different concentrations of 2, 4-D (acid). This herbicide inhibited the growth of seedlings of all these weeds effectively. The linear growth of the radicle and the hypocotyl was inhibited and growth of lateral roots was. also checked. Rate of inhibition of radicle and hypocotyl increased at higher concentrations. It caused swellings of the radicle and the hypocotyl of A. aspera and C. tara seedlings. No such swellings were seen in R. tuberosa- The radicle of all the three species were more susceptible to 2,4-D than the hypocotyl. 100 ppm was found lethal for A. aspera and C. tara and 200 ppm for R. tuberosa seedlings. The results were discussed with reference to the strength of the concentrations and their pH values.