Epicuticular wax on leaves of field-grown honey mesquite (Prosopis glandulosa Torr.) trees consisted of 35% esters, 32% alkanes, 25% free fatty alcohols, and 7% free fatty acids. Aldehydes were present in very low concentrations. The number of carbon atoms (Cn) of alkanes ranged from 25 to 31, with a maximum (57%) at 29. Esters consisted of fatty acids with Cn of 16, 18, and 20, with most (70%) at 18 and fatty alcohols with Cn of 24-32. The Cn of free fatty alcohols and free fatty acids also ranged from 24 to 32. Only primary alcohols were present. Immediately after exposure of glasshouse-grown seedlings to 14CO2 for 4 h, 60% of the recovered 14C was incorporated into free fatty acids; the percentage decreased progressively to 18% 8 h after exposure and remained stable thereafter. The proportion of 14C in free fatty alcohols increased from ca. 12% immediately after exposure to 14CO2 to 55% at 8 h. Little 14C was associated with other wax components over the 24-h period; 3% or less was incorporated into al...