Acacia. LEGUMINOS.E. -iqo 



species). Stamens 10, free, exscrted; anthers tipped with a deciduous glund. 

 Ovary villous (in American species) : stylo filiform. Pod hnear, compressed or 

 nearly terete, straight, falcate, or twisted, coriaceous and indehiscent, usually becom- 

 ing thick and spongy within, and with thick partitions between the seeds. Seeds 

 numerous, ovate, compressed. — Trees or shrubs, often armed with axillary spines 

 or spinescent stipules ; leaves bipinnate, with 1 or 2 pairs of pinnce, and usually 

 numerous small entire leaflets; flowers small, greenish, in cylindrical or globose 

 axillary pedunculate spikes. 



Species about 18, of which 5 belong to Africa and tropical Asia, the remainder to Jlcxico and 

 South America, the following extending into the United States. 



* Pod elongated, straight or falcate, compressed or at length thickened and fleshy : 

 seeds each in a distinct cartilaginous envelope: spines axillary: spikes cylindrical. 

 — Algarobia, Benth. 



1. P. juliflora, DC. A shrub or tree (sometimes 30 to 40 feet high), g]al)rous 

 or puberulent, with stout axillary spines or often unarmed : leaflets <) to 30 i)airs, 

 short-oblong to linear, 3 to 18 lines long, obtuse or acute : spikes shortly peduncled' 

 2 to 4 inches long, usually dense, 1 - S-fruited : flowers nearly sessile, a line long : 

 pod 4 to 6 inches long or more, straight or curved, at first flat and constricted 

 between the seeds, 3 to 6 lines broad, at length sweet and pulpy within, acuminate, 

 longitudinally veined ; stipe 3 to 6 lines long. — Prodr. ii. 447 ; Benth. in Trans, 

 Linn. Soc. xxx. 377. P. glandulosa, Torrey, Ann. IST. Y. Lye. ii. 192, t. 2. Alga- 

 robia glandidosa, Torr. & Gray, Fl. i. 399 ; Gray, PI. Wright, i. GO. Prosopis 

 odorata, Torr. in Frem. Eep. 313, t. 1, excL fruit. 



This is the Algaroba of the Mexicans, or Honey Mes(j[uit, found as a small shrub iu Southea.st- 

 ern California from San Felipe Canon to Fort Mohave, and eastward to Texas. The species in 

 various forms extends southward through JVIexico, and along the Andes to Chili, and to Buenos 

 Ayres. The abundant fruit is eaten by the Indians and often by whites, and is a valualilc food 

 for horses. The shrub also furnishes a valuable gum, resembling Chim Araljic, which in Texas and 

 Mexico is collected in considerable quantity for export. 



* % Pod thick, spircdly twisted in numerous turns: stipides spinescent: spikes glo- 



bose to cylindrical. — Strombocarpa, Benth. 



2. P. pubescens, Benth. A shrub or small tree 15 to 30 feet high, resem- 

 bling the last, canc8cently puberulent or glabrate : leaflets 5 to 8 pairs, oblong, 3 to 

 4 lines long, acutish : spikes lax, IJ to 2 inches long, on peduncles about equalling 

 the leaves, several-fruited: flowers sessile, 1-|- lines long: ovary very villous : pod 

 twisted into a narrow straight cylinder 1 or 2 inches long, pulpy Avithin, nearly 

 sessile. — Lond. Jour. Bot. v. 82, & I c. 380. Strombocarjms imbesceus, (ir.iy; 

 Torrey, Pacif. R. Eep. v. 360, t. 4. Prosopis Pmoryi, Torrey, Emory Pep. 139. 



The Tornilla of the Mexicans, and Screw-bean or Screw-pod Mesiiuit of the Americans. In San 

 Diego Co.at Vallecito {Thurber), Mountain Springs {Palmer), Foit Mohave (Cooper), and cast to 

 New Mexico. The pods are ground into meal and used for food l)y the Indians. P. cim-rd-frois, 

 Gray, a species of the Rio Grande Valley with similar fruit, has much smaller leaves and loallots, 

 the common petiole nearly obsolete, the slender spines usually exceeding the leaves, and the 

 flowers in long-peduncled globose lieads. 



21. ACACIA. 



Flowers perfect or polygamous. Calyx 4 -5-toothed. Petals more or less united 

 below. Stamens numerous, exserted, free or united at base ; anthers small. Stylo 

 filiform. Pod 2-valved or indehiscent, many-seeded, compressed and membrana- 

 ceous or more or less thickened and rounded. S(>eds compressed : alliumcn none. 

 — Shrubs or trees, often spinose or prickly ; leaves bipinnate, with small leaflets ; 



