The response of the facultative hemiparasitic angiosperm Rhinanthus minor to inorganic solutes was investigated by supplying plants not attached to a host with nitrogen, phosphorus and potassium. Solutes were supplied both individually (in pots) and in combination (under field conditions). Only phosphorus resulted in any significant stimulation of growth. The phosphorus treated plants also had higher rates of light saturated photosynthesis and higher water use efficiencies than control plants. In contrast to many autotrophic plants, nitrogen neither stimulated growth nor photosynthesis.