Cuttings of one herbaceous and of four dormant woody plants were treated with a series of talc dusts containing indolylacetic acid and the acids and potassium salts of several members of the naphthyl series of root growth stimulating chemicals. The higher members of the series compared favourably with naphthylacetic acid in respect to most of the responses considered, though there were indications that naphthylacetic acid or its salt had a greater effect on the number of roots per rooted cutting. Naphthylacetic and 1-γ-naphthylbutyric members of the series were equally effective as acids or salts; however, a mixture of the isomeric 1- and 2-γ-naphthylbutyric acids was more active than the corresponding mixture of salts. Conversely, potassium naphthylhexoate appeared to have greater activity than the acid. The results suggest that pure naphthylbutyric acid, the isomeric mixture of acids, and potassium naphthylhexoate are virtually as effective as the recognized plant growth stimulating chemicals, indolyl- and naphthylacetic acids.A noteworthy feature of the results was the beneficial effect of treatment with talc alone. The promotion of new growth and rooting of dormant cuttings were of particular interest, though most of the other criteria studied also indicated beneficial responses.