600 TREES OF NORTH AMERICA 



opening by marginal sutures; ovary stipitate, villose; style filiform, with a minute terminal 

 stigma. Legume linear, compressed or subterete, straight or falcate, or contorted or 

 twisted into a more or less regular spiral, indehiscent; the outer coat thin, woody, pale 

 yellow, inclosing a thick spongy inner coat of sweet pulp containing the seeds placed 

 obliquely and separately inclosed, their envelopes forming nut-like joints. Seeds oblong, 

 compressed, the hilum near the base; seed-coat crustaceous, light brown, lustrous; em- 

 bryo surrounded by a layer of horny albumen; radicle short, slightly exserted. 



Prosopis is distributed in the New World from southern Kansas to Patagonia, and in 

 the Old World is confined to tropical Africa, and to southwestern and tropical Asia. 

 Sixteen or seventeen species have been distinguished. Of the three species found in the 

 territory of the United States two are small trees. 



Prosopis produces hard durable wood, particularly valuable as fuel, and the pods are 

 used as fodder. 



The generic name is from irpoo-wn-is, employed by Dioscorides as a name of the Burdock. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES. 



Legume compressed or ultimately convex; p'mnse 12-22-foliolate. 



1. P. juliflora (C, E, G, H). 

 Legume thick, spirally twisted; pinnae 10-16-foliolate. 2. P. pubescens (E, F, G, H). 



1. Prosopis juliflora DC. Mesquite. Honey Locust. .> 



Leaves with 2 or rarely 4 pinnae, and slender terete petioles abruptly enlarged and 

 glandular at base; stipules linear, .acute, membranaceous, deciduous. Flowers appearing 

 in successive crops from May to the middle of July, fragrant, about T y long, on short 



Fig. 550 



pedicels, in slender cylindric spikes l'-4' long, on stout peduncles %'-%' in length; 

 calyx glabrous or puberulous, about one fourth as long as the narrowly oblong acute petals, 

 glabrous or puberulous on the outer surface and covered on the inner surface toward the 

 apex with hoary tomentum; stamens twice as long as the corolla, the dark-colored con- 

 nective of the anther-cells furnished at apex with a stalked gland; ovary short-stalked, 

 clothed with silky hairs. Fruit in drooping clusters, linear, at first flat, becoming subter- 

 ete at maturity, constricted between the 10-20 seeds, straight or falcate, contracted at 

 the ends, 4'-9' long, l'-\' wide; seeds about \' long. 



A low tree, with a large thick taproot descending frequently to the depth of 40-50, 



