Prosopis juliflora (Sw.) DC.  

A tall, spreading shrub or a small tree. Branches green, thomy; the thorns usually short or stout, up to about 2.5 cm long, a modification of the leaf rachii and not stipular in origin. Leaves shortly - or long-petiolate, the petioles up to about 3 cm long : bipinnate; pinnae usually a single pair but reportedly varying from 1- 3 pairs, each pinna up to 8 cm long; leaflets usually 20 pairs or less per pinna, sometimes up to 30 pairs, glabrous, about 3 - 6 times as long as broad, usually less than 1 cm long. Spikes white, up to about 6 cm long (sometimes longer). Calyx cupulate, shortly 5-dentate, about 1 mm long. Corolla of 5, greenish petals 2.5 - 3 mm long. Pods up to 20 cm long, to about 1.2 cm wide, compressed but turgid, straw-colored, straight or strongly falcate, more or less constricted between seeds, beaked.
• Remarks: Mesquite has been a subject of controversy concerning its allergenic nature. Also, when planted as avenue trees, its branches tend to break under their own weight.