In 1934, Bennetts teamed with state botanist Charles Gardner to study the toxic effect of native plants species on sheep. Gardner would collect the plants and supply them fresh to Bennetts who would then feed them to the sheep. They confirmed 24 species of plants as being poisonous, most which were from the native pea genera "Gastrolobium" and "Oxylobium". Based on this and later research, Gardner and Bennetts published "The Toxic Plants of Western Australia" in 1956. During 1935, investigations into the effects of castrating male lambs with either mechanical pincers compared to using a knife, both of these methods have since been replaced with rubber elastrator rings. The experiment on 499 sheep concluded that no significant differences were observable in respect of mortality, maturity rates and meat quality.