Monthly (May to August) midday SWPs measured in two saltbush shrub species, A. lentiformis and A. polycarpa, at different sites (a and b). At the two sites where both species co-occurred, midday SWP are shown for each species (c and d). Values of minimum seasonal midday SWP (P_min, MPa) are presented and different letters within the two figure panels (a and b) indicate significant differences between species and sites (P < 0.05). Each symbol represents the mean ± SE (n = 6 per species per site).