An Illustrated Guide to ARIZONA WEEDS

The University of Arizona Press



PEA FAMILY-Leguminosae

WESTERN HONEY MESQUITE AND VELVET MESQUITE-Prosopis juliflora (Swartz.) DC. var. torreyana Benson and var. velutina (Woot.) Sarg.

DESCRIPTION-A spiny deciduous shrub or small tree up to 30 or exceptionally 55 feet high, with a trunk 1 to 4 feet in diameter. Usually armed with stout yellowish, nearly straight spines arising in pairs, 1/4 to 3 inches long. The leaves, 3 to 8 inches long, are first divided into 1 to 2 pairs of primary divisions. Each of these is again divided into about 10 to 28 pairs of finely hairy or hairless secondary leaflets, 1/8 to 3/4 inch long.

The small fragrant greenish yellow flowers are crowded on stalked spikes 2 to 5 inches long. The flat tan colored leatherish pods are finely hairy or hairless, 3 to 8 inches long, with a sweetish pulp. The rough bark separates into dark strips, and the wood is hard, reddish brown, with thin yellow sapwood.

DISTRIBUTION-Mesquite is abundant throughout southern and central Arizona, and also occurs in northern Arizona in Coconino and Mohave counties, 1,000 to 5,000 (rarely 6,000) feet elevation; flowering March to August, principally May to June. It is a common tree along the watercourses, washes, and alluvial bottoms where ground water is available. In some areas, the roots may penetrate to depths of 60 feet.

Mesquite is abundant, and has become a serious range problem on the mesas and slopes of the deserts and desert grassland ranges, and occasionally lower oak woodlands where it is often a shrub. The carrying capacity of many ranges has been seriously reduced due to its tremendous increase. Dissemination of the seeds in cattle dung has been an important factor in this invasion. Mesquite pods are relished by all livestock, which, unlike most other pea pods, do not shed their seeds.

POISONOUS PROPERTIES-Livestock are sometimes bothered after eating mesquite beans. This is not due to a poison, but to the formation of large hard balls from the long, tough, stringy margins from green or rain-soaked dried pods. Dried beans are not harmful, as the thick fibers easily break into short pieces when eaten.

Copyright (c) 1972 The Arizona Board of Regents

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