LEGUMINOSE. SILVA OF NORTH AMERICA. 103 
red; this surrounds a thick spongy layer of sweet pulp in which the seeds are placed obliquely, sepa- 
rately inclosed in thin envelopes forming nut-like joints quadrate by mutual pressure. The seeds are 
oblong, flattened, with a thin light brown lustrous testa and thin horny albumen. 
Prosopis juliflora is distributed in the United States from the southern borders of Colorado and 
Utah through New Mexico, the southern borders of the Indian Territory and northern and western 
Texas to the Rio Grande, and through southern Nevada and Arizona to southern California. The 
eastern limits of its range may be represented by a line extending from a point where the thirty- 
seventh parallel of latitude intersects the one hundredth meridian to the neighborhood of Dallas in 
Texas, and then southward to the valley of the Colorado and along the Gulf at a distance of twenty 
or thirty miles from the coast, which it reaches near the mouth of the Rio Grande; and its western 
limit by a line extending from the Tejon Pass in California by Los Angeles to San Pedro on the Pacific 
coast. The Mesquite is generally distributed through northern Mexico? and Lower California,’ and is 
abundant in the Andean region, extending south as far as Chile; it is widely spread in the Argentine 
Republic, and has become naturalized in the arid regions of southern Brazil* and in the drier parts of 
the island of Jamaica.’ 
In the United States the Mesquite attains its greatest size in those bottom-lands of the rivers of 
southern Arizona where it is protected from the wind and where the water-level is not far below the 
rich porous surface of the soil. Favored by such conditions it often forms open forests of considerable 
extent ; it is at home on rich prairies, from which fire recurring year after year cannot drive it, on arid 
rocky hills, on sandy and saline flats, and on shifting sand dunes. A hot dry climate with mild winters, 
a small rainfall, and a clear atmosphere suits it best; but it can withstand many degrees of frost, and 
in tenacity of life and ability to struggle against conditions which would exterminate most plants it is 
not surpassed by any other tree. 
The wood of Prosopis juliflora is heavy, hard, and close-grained, although not very strong; it 
contains numerous distinct medullary rays and many evenly distributed open ducts, and is rich dark 
brown or sometimes red, with thin clear yellow sapwood. The specific gravity of the absolutely dry 
wood is 0.7652, a cubic foot weighing 47.69 pounds. 
soil, and is valued and largely used for fence-posts and railway ties ; it furnished the underpmnings and 
It is almost indestructible in contact with the 
timbers of the adobe buildings of the early inhabitants of western Texas, New Mexico, Arizona, and 
northern Mexico ; it is sometimes used in furniture, for the fellies of heavy wheels, and for the pave- 
ments of city streets ; and it affords the best and often the only fuel in the regions where it grows, 
burning slowly with a bright clear flame. It produces valuable charcoal, but is unsuited for the genera- 
The 
tion of steam on account of the destructive action upon boilers of the tannin ® which it contains. 
1 The variations in the size and shape of the leaflets of Prosopis 
juliflora, the absence or presence of spines on different branches 
of the same individual or at different periods of its growth, and 
the innumerable forms assumed by the fruit in ripening have led 
to the publication of a large number of species which were often 
established upon fragmentary specimens, and are now referred to 
it by Bentham as synonyms. (See Bentham, Trans. Linn. Soc. xxx. 
378 [Rev. Mim.]}.) 
2 Hemsley, Bot. Biol. Am. Cent. i. 344. 
8 Brandegee, Proc. Cal. Acad. ser. 2, ii. 152 (Pl. Baja Cal.). 
4 Bentham, Martius Fl. Brasil. xv. pt. ii. 289. 
6 According to Browne (Nat. Hist. Jam. 252) Prosopis juliflora, 
which he ealled “ Afimosa diffusa, spica oblonga, siliquis lor gioribus 
compressis,”” had been introduced into Jamaica from the mainland 
and was already (1756) flourishing “ luxuriantly in many parts of 
the lowlands, where it is observed to rise, frequently to the height 
of fourteen or fifteen feet, cr better.” (See also Barham, Hort. 
Amer. 150.— Lunan, Hort. Jam. i. 156.— Macfadyen, Fl. Jam. 
311.) 
6 An analysis of the wood of Prosopis juliflora made by the 
chemist of the Department of Agriculture of the United States 
shows 6.21 per cent. of tannic acid in the heartwood, 0.50 per cent. 
inthe sapwood, and 0.50 per cent. in the bark. (W. McMurtree, Rep. 
Dept. Agric. 1873, 183.) It is almost identical with the tannic acid 
found in oak-galls, although it is claimed that it acts more quickly 
on animal tissues and penetrates hides more rapidly than either 
The color of the heartwood is due to a 
pigment probably associated with the tannin, the two being extri- 
cable together by hydrated ether ; and Havard suggests (Am. Nat. 
xviii. 458) that the relative proportion of tannin in any log can be 
judged of by the extent and deepness of its color, and that, like the 
oak or sumach tannin. 
color, it increases with the age of the tree. An astringent decoction 
obtained by boiling chips of the heartwood may be used to check 
diarrhea or dysentery, or by infusion to purify muddy or stagnant 
(Havard, l. c.) 
water. 
