LEGUMINOS. SILVA OF NORTH AMERICA. 115 
ACACIA. 
FLoweErs perfect or polygamous, in globose heads or cylindrical spikes; calyx 4 or 
d, rarely 3-parted, the divisions valvate in estivation, or sometimes almost wanting ; 
petals as many as the divisions of the calyx, valvate in estivation; stamens indefinite, 
free or slightly connected at the base; ovary 2 or many-ovuled. Legume 2-valved or 
indehiscent. Leaves bipinnate. 
Acacia, Adanson, Fam. Pl. ii. 319. — Meisner, Gen. 96.— Aldina, E. Meyer, Comm. Pl. Afr. i. 171 (not Adanson nor 
Endlicher, Gen. 1326.— Bentham & Hooker, Gen. i. 594.— Endlicher). 
Baillon, Hist. Pl. ii. 68. Farnesia, Gasparini, Descr. Nuov. Gen. Leg. 
Vachellia, Wight & Arnott, Prodr. Fl. Ind. 272.— Meisner, Tetracheilos, Lehmann, Pl. Preiss. ii. 368. 
Gen. 96. — Endlicher, Gen. 1326. Chithonanthus, Lehmann, Pl. Preiss. ii. 368. 
Arthrosprion, Hasskarl, Retzia, i. 212. 
Trees, shrubs, or occasionally herbs, with unarmed aculeate or spinescent branches. Leaves bipin- 
nate ; leaflets usually small, in many pairs; or reduced to simple phyllodia or dilated petioles; stipules 
spinescent or inconspicuous, rarely membranaceous. Peduncles axillary, solitary, or fascicled, or pani- 
cled at the ends of the branches, generally furnished, either at the apex, towards the middle, or near 
the base, with two short connate scale-lke bracts. Flowers perfect or often polygamous, in globose 
heads or cylindrical spikes, small, generally yellow or greenish white, in the axils of minute linear 
bractlets more or less dilated and often peltate at the apex. Calyx campanulate, dentate, lobed or 
divided into distinct sepals sometimes reduced to minute hairs. Petals more or less united, rarely 
free, very rarely wanting. Stamens numerous, usually more than fifty, exserted, free or slightly and 
irregularly united at the base, inserted under or just above the base of the ovary; filaments filiform ; 
anthers small, attached on the back, versatile, introrse, two-celled, the cells opening longitudinally ; 
pollen grains generally aggregated into two to four masses in each cell. Ovary sessile or stipitate, two 
or many-ovuled, contracted into a long slender style terminating in a minute stigma; ovules suspended 
from the inner angle of the ovary, two-ranked, superposed, anatropous, the micropyle superior. Le- 
gume ovate, oblong or linear, straight, faleate or variously twisted, flat or nearly cylindrical, mem- 
branaceous, coriaceous or woody, two-valved or indehiscent, continuous or variously divided within, very 
rarely separating into one-seeded joints. Seed transverse or longitudinal, usually ovate, compressed, 
destitute of albumen ; funicle filiform or thick, colored, straight or twice or thrice folded upon itself, 
sometimes entirely surrounding the seed, often dilated at the apex into a more or less flat aril; testa 
thick, crustaceous, generally marked on the centre of each face of the seed with an oval or horseshoe- 
shaped depression or opaque spot or ring sometimes very obscure. Embryo filling the cavity of the 
seed ; cotyledons oval, flat, the radicle straight, included, slightly exserted. 
Acacia is generally distributed through the warmer parts of the world, especially in regions of 
scanty rainfall, and seems to have abounded in Europe towards the end of the Lower Eocene period.’ 
No less than four hundred and thirty-two species are now distinguished.” Australia, the headquarters 
of the genus, contains nearly three hundred species;* they abound in tropical* and southern Africa” 
and in northern Africa and the Orient,° in all the warmer regions of southern Asia,’ in the islands of 
1 Saporta, Origine Paldontologique des Arbres, 320. 5 Harvey & Sonder, Fil. Cap. ii. 279. 
2 Bentham, Trans. Linn. Soc. xxx. 444 (Rev. Min.). ® Boissier, Fl. Orient. ii. 635. 
8 Bentham, Fi. Austral. ii. 301. 7 Thwaites, Enum. Pl. Zeylan. 99. — Hooker f. Fv. Brit. Ind. ii. 
4 Oliver, Fl. Trop. Afr. ii. 337. 292. — Hemsley, Jour. Linn. Soc. xxiii..215. 
