Acacia. LEGUMEMOSiE. J53 



species). Stamens 10, free, exserted ; anthers tipped with a deciduous gland. 

 Ovary villous (in American species) : style filiform. Pod linear, 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 pinnae, and usually 

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

 axillary pedunculate spikes. 



Species about IS, of which 5 belong to Africa and tropical Asia, the remainder to Mexico 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. 

 — Algakobia, Benth. 



1. P. juliilora, DC. A shrub or tree (sometimes 30 to 40 feet high), glabrous 

 or puberulent, with stout axillary spines or often unarmed : leaflets to 30 pairs, 

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

 2 to l inches long, usually dense, 1 - 3-fruited : flowers nearly sessile, a line long : 

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

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

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

 Linn. Soc. xxx. 377. 1'. glandulosa, Torrey, Ann. X. Y. Lye. ii. 192, t. 2. Alga- 

 robia glandulosa, Torr. ifc Gray, i'l. i. 399; Gray, PI. Wright, i. GO. Prosopis 

 odorata, Torr. in Frem. Pep. 313, t. 1, excl. fruit. 



This is the Algaroba of the Mexicans, or Honey Mesquit, found as a small shrub in Southeast- 

 ern California IV Sun Felipe Canon to Fort Mohave, and eastward to Texas. The species in 



various forma extends southward through Mexico, and along the Andes to Chili, and to rtuenos 

 A\ns. The abundant fruit is eaten by the Indians and often by whites, and is a valuable food 

 for horses. The shrub also furnishes a valuable gum, resembling ' rum Arabic, which In Texas and 

 Mexico is collected in considerable quantity for export 



* * Pod thick, spirally twisted in. numerous turns: stipules spinescent: spikes glo- 



bose to cylindrical. — Strombocakpa, Benth. 



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

 bling the hist, canescently puberulent or glabrate : leaflets •"> to S pairs, oblong, 3 to 

 t lines long, acutish : spikes lax, \\ to 2 inches long, on peduncles about equalling 

 the leaves, several-fruited: Bowers sessile-, l. 1 , linos long: ovary very villous : pod 

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

 sessile-. — Lond. -lour. Bot v. 82, & 1. c 380. Strombocarpus pubescens, Gray; 

 Torrey, Pacif. R. Rep. v. 360, t. 1. Pn, .<,,/, is F.moryi, Torrey, Emory Rep. L39. 



Tin- Tornilla of the Mexicans, and Scrow-bcan or Screw-pod Mesquit of tin- Americans. In San 

 1 (iego < '". at Valleeito ( Thurber), Mountain Springs {Palmi r), Fori Mohave 1 ( 'oopi r), and east to 



New Mexico. The pods an ground int al and used for food by the Indians. /'. 



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

 the common petiole nearly obsolete, tie- slender spines usually exceeding the- have-, and the 

 Qowers in lung-pcdunclcd globose leads. 



21. ACACIA. 



Flowers perfect or polygamous. Calyx t -6 toothed. Petals more or [ess united 

 below. Stamens numerous, exserted, free or united al base; anthers small. Style 

 filiform, l'o'l 2-valved or indehiscent, many-s led. compressed ami membrana- 

 ceous or more or less thickened and rounded. Seeds compressed : albumen none. 

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



