Acacia. LEGUMINOSJi:. 



163 



specii's). Stiinicns 10, free, ex scried ; iintli(Ms tipped with a ilrcidnoiis gland. 

 Ovary villous (iu American siiecies) : stylo 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 spiuescent stipules ; leaves bipiniiatc, with 1 or 2 pairs of pinna?, and usually 

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

 axillary peduncidate spikes. 



Species about 18, of wliich 5 belong to Africa and tropical Asia, the lemainder to Mexico and 

 South America, the following extending into the United States. 



'.V Pod elongated, straufht or falcate, compressed or at length thickened and Jleshy : 

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

 — Ai^OAROBiA, Benth. 



1. P. juliflora, DC. A shrub or tree (sometimes 30 to 10 feet high), glabrous 

 or pubcruli'.nt, with stout axillary spines or often unnrmeil : leallds (1 to ."JO pairs, 

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

 2 to 4 inches long, usually dense, 1 - 3-fruitod : flowers nearly sessile, a line long : 

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

 between the seeds, 3 to 6 lines broad, at length sweet and ])ulpy within, acuminate, 

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

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

 rohia gland nlnm, Torr. & Gray, Fl. i. 309; (J ray, PI. Wright, i. GO. Prosopis 

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



This is the Algnroba of the Mexicans, or Honey Mesquit, found as a small shrul) in Southea.st- 

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

 various forms extends southward through Mexico, 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 valuable food 

 for liorses. The shrub also furnishes a valuable gum, resembling Gum Arabic, which in Texas and 

 Mexico is collected iu considerable quantity for export. 



* * Pod thick, spirally twisted in. nuvierous turns: stipules .yv'nesrent : spikes glo- 

 bose to cylindrical. — STnoMnocARPA, Beiitli. 



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

 bling the last, canescently puberulent or glabrate : leaflets f) to 8 pairs, oblong, 3 to 

 4 lines long, acutish : spikes lax, 1^ to 2 inches long, on peduncles about e(]nalling 

 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 within, nearly 

 sessile. — Lond. Jour. Bot. v. 82, & 1. c. 380. Strombocarpns pubescens, Gray ; 

 Torrey, Pacif. R. Rep. v. 3G0, t. 4. Prosopis Emoryi, Torrey, Emory Rep. L39. 



The Tornilln of the Mexicans, and Scrow-benn or Screw-pod Mesrpiit of the Americans. In Snn 

 DIpKo Co. nt Vallecito (Tliurbrr), Moniitnin Sprincs {I'ohnrr), Fort Mohave* {('ooprr), nml east to 

 New Mexico. Tlio pods nre ground into inenl iukI used for food by the Indians. /'. cincrasccns, 

 Gray, a species of the Rio (Jinnde Valley with similar Iruit, li.is much smaller leaves and leaflets, 

 the common j)etiole nearly obsolete, the slender spines usually exceeding the leaves, and the 

 flowers in long-peduneled globose heads. 



21. ACACIA, Willd. 

 Flowers ])erfect or ]H)lygamous. (!alyx 4 -^-toothed. IVtals more or less united 

 below. Stamens numerous, exserted, free or united at ba.-^e ; anthers small. Stylo 

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

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

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



