Abstract: The effects of Launaea procumbens (Roxb.) Rammaya and Rajgopal on seed germination and early seedling growth of four test plant species including mustard, bulrush millet, corn and spinach was evaluated under laboratory conditions. Aqueous extract of L. procumbens at different concentrations (25, 50, 75 and 100% stock solution) inhibited germination of three test species in the order: spinach > mustard > corn; germination of millet was not significantly influenced. Root and shoot growth of all four species was substantially reduced by Launaea extract. The growth was reduced in the order: spinach > mustard > corn > millet. When different modes of extract application were tested, it was found that only the soil application of the aqueous extract had a significant retarding effect on wheat growth while shoot spray or root dip treatment had no such effect. Decaying shoot of L. procumbens in sandy-loam at 5, 10 and 20 g/400 g soil caused substantial inhibition of germination and seedling growth of bulrush millet (Pennisetum americanum) at high dosages. Bioassay of the ether extract of L. procumbens exhibited four zones of inhibition at Rf values 0.1-0.2, 0.7-0.8, 0.8- 0.9 and 0.9-1.0 while a promoter was detected between Rf values 0.3-04. A thin-layer chromatography for the phenolics showed the presence of seven phenolic acids including: salicylic acid, vanillic acid, syringic acid, 2-methylresorcinol, gallic acid and two unknowns.