The Mesquite 529 



smooth, and reddish brown. The bark is about 8 mm. thick, dark brown, fur- 

 rowed into ridges and scaly. The leaves are evenly bipinnate, 1.5 to 2 dm. long, 

 including the slender leaf-stalk which is about 3 cm. long, with spinescent stipules 

 at its base 10 to 15 mm. long; there are about 12 pairs of distant pinnae, short- 

 stalked, with a conspicuous gland between each pair; leaflets 16 to 30 pairs, 

 lanceolate, 6 to 10 mm. long, sharp or taper-pointed and rounded on one side of 

 the oblique base, sessile or nearly so, grayish green and hairy, becoming nearly or 

 quite smooth. The flowers are in solitary or clustered globose white heads, on 

 stout peduncles 5 to 8 cm. long, which have two bracts at the end, the heads 2 to 

 2.5 cm. in diameter. The calyx is obconic, hairy at the tip of the short lobes, 

 about three fourths the length of the petals; stamens much exserted, their anthers 

 small; ovary sessile and hairy. The fruit is very flat, linear, 1.5 to 2 dm. long, 10 

 to 15 mm. wide, pointed, tapering to the short, stout stalk, finely hairy until nearly 

 ripe, when it is quite smooth. The seeds are oval, 12 mm. long, flat, notched at 

 the base, dark brown and shining. 



The wood is hard, close-grained and brown; its specific gravity is about 0.92. 



IX. THE MESQUITES ■ 



GENUS PROSOPIS LINN^US 



?|ROSOPIS includes some 15 species of trees or shrubs of dry or arid re- 

 gions of tropical and subtropical portions of both the Old World and 

 the New, most abundant in America. They are spiny or unarmed; 

 some of them are of economic value, locally, for lumber and fuel; the 

 pods of some species are used as food for both man and beast. 



The leaves, which are mostly deciduous, are evenly bipirmate, with few pinnae 

 and few or many leaflets. The perfect, greenish or yellow flowers are in spikes; 

 calyx sessile, 5-lobed; corolla of 5 free or slightly united petals; stamens 10; ovary 

 sessile or stalked, hairy or smooth, many-ovuled; style thread-like; stigma small. 

 The fruit is an indehiscent legume, linear, compressed, or nearly round, straight 

 or curved, often constricted between the seeds which are separated by a more or 

 less spongy tissue, ovate to oblong and compressed; endosperm hard. 



Prosopis is the Greek name of an unidentified plant, and why Linnaeus applied 

 it to these trees is not clear. The Persian plant Prosopis spicigera Linnaeus is the 

 type species. 



Foliage smooth. i. p. glandtdosa. 



Foliage densely hairy. 2. P. velutina. 



I. MESQUITE — Prosopis glandulosa Torrey 



Prosopis juliflora Brewer and Watson, not de CandoUe 



Also called Honey locust, Algaroba, Honey pod, and Ironwood, this is a small 

 tree with a round symmetrical head, but more often an irregular crooked branched 



