LEGUMINOS^E 545 



red and armed with stout recurved infrastipular spines flat at the base and \' long 

 and broad. Bark of the trunk about \' thick, furrowed, the surface separating into 

 thin narrow scales. "Wood heavy, very hard, strong, close-grained, durable, rich 

 brown or red, with thin light yellow sapwood of 5 or 6 layers of annual growth. 



Distribution. Dry gravelly mesas, the sides of low canons and the banks of 

 mountain streams; valley of the Rio Grande, western Texas, through southern New 

 Mexico and Arizona to southern California; and in northern Mexico. 



4. LEUCJBNA, Benth. 



Trees or shrubs, with slender unarmed branches. Leaves persistent, abruptly bipin- 

 nate, with numerous pinnae and small leaflets in many pairs, petiolate, their petioles 

 often furnished with a conspicuous gland below the lower pair of pinnse; stipules 

 minute and caducous, or becoming spinescent and persistent. Flowers minute, white 

 mostly perfect, sessile or short-pedicellate, in the axils of small peltate bracts villose 

 at the apex, in globose many-flowered pedunculate heads, the peduncles in axillary 

 fascicles or in leafless terminal racemes; calyx tubular-campanulate, minutely 

 5-toothed; petals 5, free, acute or rounded at the apex, narrowed at the base; 

 stamens 10, free, inserted under the ovary, exserted; filaments filiform; anthers ob- 

 long, versatile; ovary stipitate, contracted into a long slender style, with a minute 

 terminal slightly dilated stigma. Legume many-seeded, stipitate, linear, com- 

 pressed, dehiscent, the valves thickened on the margins, rigid, membranaceous, con- 

 tinuous within, their outer coat thin and papery, dark-colored, the inner rather 

 thicker, woody, pale brown. Seeds obovate, compressed, transverse, the hilum near 

 the base, suspended on long slender funicles ; seed-coat thin, crustaceous, brown 

 and lustrous; embryo inclosed on its two sides by a thin layer of horny albumen; 

 radicle slightly exserted. 



Leucsena with nine or ten species is confined to the warmer parts of America 

 from western Texas to Peru and Venezuela, and to the islands of the Pacific Ocean 

 from New Caledonia to Tahiti, where one species has been recognized. Of the three 

 indigenous species found in the territory of the United States, two are arborescent. 

 Leuccena glauca, L., a small tree or shrub, cultivated in all warm countries, and a 

 native probably of tropical America, is now naturalized on Key West, Florida. 



The generic name, from \tvxulvu, refers to the color of the flowers. 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Peduncles bibracteolate at the apex ; leaves 10-14-pinnate ; pinnae with 15-30 pairs of leaf- 

 lets ; stipules becoming 1 spinescent, persistent. 1. L. Greggii (E). 



Peduncles without bracts ; leaves 30-36-pinnate ; pinnae with 30-60 pairs of leaflets ; 

 stipules minute, caducous. 2. L. pulverulenta (E). 



1. Leucaena Greggii, Wats. 



Leaves 6'-7' long and broad, with slender rachises furnished on the upper side 

 with a single elongated bottle-shaped gland between the stalks of each pair of pinnae; 

 pinnae 10-14, remote, short-stalked, with 15-30 pairs of leaflets; stipules gradually 

 narrowed into long slender points, becoming rigid and spinescent, ' to nearly 

 ^' long and persistent for two or three years; leaflets lanceolate, acute or acumi- 

 nate, often somewhat falcate, nearly sessile or short-petiolulate, full and rounded to- 

 ward the base on the lower margin, nearly straight on the upper margin, gray-green, 



