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ground forests”—and furnishes a cheap and valuable fuel. The tim- 
ber is heavy, very hard, and possesses remarkable durability. It is 
employed chiefly for fuel, tie-timber, and fencing, but somewhat for 
heavy wheel stock and in the manufacture of charcoal. 
Description.—Leaves compound, twice pinnate, single or in clusters, with a pair of 
stiff, straight, yellowish thorns $ to 4 inch long at the base of each leaf-stalk- or 
cluster; leaflets 4 to 1 inches long, by +; to 4 of an inch wide, elliptic-oblong to lance- 
linear. A cup-shaped gland at the end of the main leaf-stem, (where the usually 
single pair of smaller stems (pinn) with leaflets is given off). Pods somewhat flat- 
tened, straightish or curved, 3 to 74 inches long, } to } an inch wide; composed of 12 
to 25 lobe-like joints (containing as many seeds), and terminating in an awl-point; 
young pods covered with a dense velvety down, yellowish-white when mature. They 
have a sweet taste, and are often used for fodder. 
40.—ScREW BEAN. SCREW-POD. MESQUIT. TORNILLA. (Prosopis 
pubescens, Benth.) 
A small tree or shrub growing on gravelly or sandy bottom-land, 
through New Mexico (in western Texas, through Arizona to California; 
southward into Mexico); said to attain its largest size within the 
United States in the valleys of the lower Colorado and Gila Rivers— 
20 to 25 feet in height, and 6 to 12 inches in diameter. The wood is 
heavy, very hard, and brittle, but exceedingly durable, and is used for 
fencing and fuel. Pods sweet, sometimes used for fodder, and for flour 
by Indians. 
Description.—Leaves essentially as in Prosopis juliflora (No.39), with a pair of 
straight pearly-white thorns at base of each leaf or cluster; leaflets elliptic-oblong, 
often with a short fine point (probably less variable in size than those of the preced- 
ing species), ¢ to 4 an inch long, and ;'; to} of an inch wide. Pods cylindrical, 1 
to 24 inches long, { to ¢ of an inch in diameter, straightish or crooked, closely coiled 
inaspiral; clothed with a fine velvety down; light brown at maturity. Branchlets 
with white longitudinal (decurrent) lines proceeding from the bases of the thorns. 
41.—CA’s CLAW. (Acacia Greggit, Gray.) 
Often a shrub, or alow much-branched free, 20 to 25 feet in height and 
sometimes 19 inches in diameter, growing abundantly on the dry table- 
Jands and in the low canyons of southern Utah {Dr. Palmer), New Mex- 
ico and Arizona (extending to California; also in northern Mexico and 
western Texas). The wood is heavy, very hard and strong, furnishing 
good fuel. Large trees often hollow. 
Description.—Leaf-stems short, giving off 2 to 3 pairs of smaller stems (pinn) which 
bear 3 to 6 pairs of very small (4 to 4 of an inch long) oblong-ovate (broader above) 
unequal-sided leaflets, with a rounded or abrupt apex, downy. Pods smooth, flat, 
curved, 3 to 6 inches long, and 4 to ? of an inch broad; usually with constrictions 
between the seeds; the latter flat, obicular, and dark brown. Branches sparingly 
armed with short hooked prickles, or occasionally unarmed, sometimes with whitish 
lines. 

