Water relations of the parasite: host relationship between the mistletoe Amyema linophyllum (Fenzl) Tieghem and Casuarina obesa Miq.

Seasonal and diurnal gas exchange and water relations of Amyema linophyllum and its host Casuarina obesa were studied at Gingin Western Australia. As recorded elsewhere for other species of mistletoe, stomatal conductances and transpiration rates were consistently higher in parasite than host, but assimilation rates did not differ significantly between partners, and water use efficiency was accordingly substantially lower in the parasite. Parallel responses of the species to environmental conditions suggested closely coordinated stomatal behaviour.