MESQUITE or HONEY LOCUST, in botany, a tree, native of arid regions in the south-western United States and extending southwards to Chile and the Argentine Republic. It is known botanically as Prosopis juliflora, and belongs to the family Leguminosae (suborder Mimoseae). It reaches 4o or 5o ft. in height with a trunk usually not more than 6 to I2 in. in diameter, and divided a short distance above the ground into numerous irregular crooked branches. The remarkable development of its main root in relation to water-supply renders it most valuable as a dry-country plant ; the root descends to a great depth in search of water, and does not branch or decrease much in diameter till this is reached. It can thus flourish where no other woody plant can exist, and its presence and condition afford indications of the depth of the water-level. When the plant attains the size of a tree, water will be found within 4o or 5o ft. of the surface; when it grows as a bush, between 5o or 6o ft.; when the roots have to descend below 6o ft., the stems are only 2 or 3 ft. high. These woody roots supply valuable fuel in regions where no wood of fuel value is produced above ground. The wood is almost
indestructible in contact with soil, and is largely used for fence posts and railway ties. The ripe pods supply a nutritious food and a gum resembling gum arabic exudes from the stem.
An allied species Prosopis pubescens, a small tree or tall shrub, native of the arid regions of the south-western United States, from western Texas to southern Utah, Nevada and California and south to Mexico, is known as the screw-bean or screw-pod mesquite from the fact that the pods are twisted into a dense screw-like spiral; they are used for fodder and are sweet and nutritious, but smaller and less valuable than those of the mesquite. The valuable fodder grasses of the prairies of the United States known as mesquite grasses, belong to the genus Boutelona.
See C. S. Sargent, Silva of North America (1892) ; G. B. Sudworth, Forest Trees of the Pacific Coast (1908) ; and W. L. Jepson, Trees of California (19°9) and Manual of the Flowering Plants of California (1925).