AbslraetIn nutrient agar comparative concentrations (10"^ to 10^'' M) of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) were generally more inhibitory to the growth of tissue cultures of soybean {Glycine max (L.) Merrill cv. Acme) and cottonwood {Populus deltoides Marsh.) than were either 4-amino-3,5,6-trichloropicolinic acid (picloram) or 3,6-dichloro-o