Argentine Mesquite

The Argentine Mesquite is a semi-evergreen, upright, vase-shaped tree with a broad canopy, which grows to 10 m in height and spread. P. alba together with P. chilensis and P. juliflora were introduced into the Kingdom and Gulf States as roadside trees, and for other ornamental purposes. This handsome tree is well adapted to arid habitats, and has been seen to grow well in Arriyadh. Its short trunk has a thin, greyish-brown bark. Delicate, bluish-green, bipinnate leaves with paired leaflets are more closely spaced than those of other Prosopis species. The tiny flowers, which attract bees, are yellowish catkins which bloom in spring; fruit pods are up to 20 cm long and generally highly curved. Stems and trunks sometimes bear large thorns in a zigzag fashion; the bark is dark and rough. Trees require full sun and reflected heat, and will grow in poor, alkaline, saline soils and have deep roots reaching the water table. Requiring no irrigation after establishment, periodic deep watering improves appearance. They cannot withstand a series of heavy frosts. Propagation is by seed and cuttings. Maintenance requirements are high, owing to pod, flower and leaf litter, and the plants need training, secure staking and pruning in late summer for a strong structure. P. alba has landscape value as a small shade tree, in street medians, buffer zones, screens and windbreaks, and is effective in parks, but is not suitable for lawns. Possible problems and other cultural requirements are the same as for P. juliflora.