MESQUITE, or Honey Locust, in botany, a tree, native of the southern United States and extending southwards through Mexico and the Andean region to Chile and the Argentine Republic. It is known botanically as Prosopis juliflora, and belongs to the natural order Leguminosae (suborder Mimoseae). It reaches 40 or 50 ft. in height with a trunk usually not more than 6 to 12 in. in diameter, and divided a short distance above the ground into numerous irregular crooked branches forming a loose straggling head. 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 almost certain indications of the depth of the water-level. When the plant attains the size of a tree, water will be found within 40 or 50 ft. of the surface; when it grows as a bush, between 50 or 60 ft.; while, when the roots have to descend below 60 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 leaves are compound, the main axis bearing two or sometimes four secondary axes on which are borne a number of pairs of narrow bluntish leaflets. The minute greenish-white fragrant flowers are densely crowded on slender cylindrical spikes from 112 to 4 in. long; the long narrow pods are constricted between the seeds, of which they contain from ten to thirty surrounded by a thick spongy layer of sweet pulp. The wood is heavy, hard and close-grained but not very strong; it is almost indestructible in contact with soil, and is largely used for fence-posts and railway ties. The ripe pods supply the Mexicans and Indians with 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, 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.
For a fuller account of these trees see Charles Sprague Sargent, Silva of North America, iii. p. 99 (1892).