LEGUMINOS.E 



601 



and furnished with radiating horizontal roots spreading in all directions and forming a 

 dense mat, a trunk 6'-8' in diameter, divided a short distance above the ground into many 

 irregularly arranged crooked branches forming a loose straggling head, and slender branch- 

 lets at first pale yellow-green, turning darker in their second year, furnished in the axils 

 of the leaves of their first season with short spur-like excrescences covered with chaffy 

 scales, and armed with stout straight terete supra-axillary persistent spines ^'-2' long, 

 or rarely unarmed; more often a shrub, with numerous stems only a few feet high. Bark 

 of the trunk thick, dark reddish brown, divided by shallow fissures, the surface separating 

 into short thick scales. Wood heavy, close-grained, rich dark brown or sometimes red, 

 with thin clear yellow sapw r ood; almost indestructible in contact with the soil, and largely 

 used for fence-posts, railway-ties, the underpinnings of buildings, and occasionally in the 

 manufacture of furniture, the fellies of wheels, and the pavements of city streets; the 

 best fuel of the region, and largely made into charcoal. The ripe pods supply Mexicans 

 and Indians with a nutritious food, and are devoured by most herbivorous animals. A 

 gum, resembling gum-arabic, exudes from the stems. 



Distribution. Western Texas and eastern New- Mexico, and on the island of Jamaica; 

 eastward and westward diverging into two extreme forms. These are 



Prosopis juliflora var. glandulosa Cock. 



Leaves 8'-10' long, 2-pinnate, with long slender petioles, the pinnae 12-20-foliolate; 

 leaflets distant, linear, mostly acute, glabrous, dark green, often 2' long and |'-j' wide. 



Fig. 551 



Flowers with a usually glabrous calyx. Fruit occasionally conspicuously constricted be- 

 tween the seeds (f. constritta Sarg.). 



A round-topped tree, often 20 high, with a trunk a foot in diameter, and long gracefully 

 drooping branches forming a symmetrical round-topped head. 



Distribution. Eastern Texas to western Louisiana (near Shreveport, Caddo Parish), 

 western Oklahoma and southern Kansas, and southward into northern Mexico. The 

 common Mesquite of eastern Texas; reappearing with rather shorter and more crowded 

 leaflets in Arizona, southern California, and Lower California. 



Prosopis juliflora var. velutina Sarg. 



Leaves 5'-6' long, often fascicled, 2-4-pinnate, cinereo-pubescent, with short petioles, 

 the pinnse 12-22-foliolate; leaflets oblong or linear-oblong, obtuse or acute, crowded, pale 

 green, j' 5' long. Flowers in densely-flowered spikes 2'-3' long; calyx villose. 



