40 



NATURAL HISTORY OF PLANTS. 



phyllocle (figs. 32, 33), while the leaflets abort more or less completely. 

 The petiole often bears one or several glands. The stipules may be 

 membranous, absent, ill-developed, or transformed into spines of 

 sometimes considerable length (fig. 28). The flowers are generally 

 small, forming globular capitula (figs. 28-32) or cylindrical cymes 

 (fig. 31), each axillary to a bract, and sometimes articulated at the 

 base. The spikes and capitula are solitary axillary, collected into 

 racemes, or forming more or less ramified inflorescences terminating 

 the branches. About four hundred species have been described in 

 this genus ; they have been grouped into more or less natural sec- 

 tions, based on the habit and inflorescence ; for the characters of the 

 fruits have been found inadequate to found well-defined subdivisions. 

 Acacias are especially abundant in Australia and Africa, but species 

 are also found in warm countries all over the world. 1 



1 It was found impossible to divide the known 

 species, upwards of four hundred in number, into 

 subgenera or sections founded on the pod, for 

 that is polymorphous, and every possible transi- 

 tion between the various forms is found. Ben- 

 tham, who has so long occupied himself in the 

 study of this genus, has divided it into six 

 secondary series based ou the habit and inflo- 

 rescence. These are as follows : — 



I. Phyllodiaece. — Species with laterally flat- 

 tened or rounded phyllodes, the leaflets abortive, 

 except in the first leaves of the plant, or on some 

 adult branches (tig. 33). Sometimes the leaves 

 are replaced by short scales or bracts. To tliis 

 group belong the genera CMthonanthus and Te- 

 tracheilos of Lejimann {Plant. Prt 188., ii. 

 368), founded only on the form of the fruit. 

 This genus contains nearly three hundred 

 Australian species, besides five or six from the 

 islands of the Pacific. (Lajik., in Journ. Hist. 

 Nat., i. t. 15. — Labile., Sert. Austr.-Caled., 

 t. 88, 89. — A. Geay, Bot. Unit. States Expl. 

 Exped., t. 53. — It. Be., in Ait. Sort. Kew., 

 ed. 3, v. 464. — Lindl., Swan Riv., App., 15. — 

 Meissn., in PI. Preiss., ii. 199.— A. CVJSTS., in 

 Field N. S. Wales, 343.— Bentii., in Hook. 

 Journ., i. 323; Ft. Austral., ii. 319. — P. 

 Muell., Fragm., iii. 127, 151.) 



II. Botrgcephalee. — Australian species, ten in 

 number, with (lowers forming globular capitula 

 collected into simple or ramified axillary or 

 terminal racemes. Leaves bipinnato, stipules 

 absent or ill-developed. (Vent., Jard. Cels., 

 t. 1; Jard. Malmais., t. 21, 61. — Ande., in 

 Pot. Repos., t. 235. — Sweet, Fl. Austral., 

 t. 12.— Hook., in Bot. Mag., t. 1263, 1750.— 

 Bot. Reg. (1843), t. 46.— Reichb., Icon, et 

 Descr. Plant., t. 73. — Link., Enum. Hort. 

 Berol., 445. — R. Be., in Ait. Hort. Kew., ed. 3, 



v. 467. — Bentii., in Rook. Journ., i. 383 ; Fl. 

 Austral., ii. 113.) 



III. Pulchellce. — Low trees, much branched 

 unarmed, rarely possessing axillary spines ; 

 leaves bipinnate ; stipules absent or ill-developed. 

 Flowers in globular capitula, rarely spicate; 

 peduncles axillary, solitary or fascicled. Species 

 Australian, numerous. (Labill., Nouv.-Holl., 

 ii. 88, t. 238.— A. DC, PI. Ear. du Jard. de 

 Geneve, note 6, t. 3. — Hook., in Bot. Mug.. 

 t. 2188, 4588, 4653, 5191.— Bot. Reg., t. 1521. 

 — P. MfEi.i.., PI. Victor., ii. t. Suppl. 12. — 

 Lindl., Swan Rie., App., 15. — Link., Enum. 

 "Sort. Berol., ii. 444. — Meissn., in PL Preiss., 

 ii. 201.— liiMU., in Hook. Journ., i. 387; Fl. 

 Austral., ii. 416.) 



IV. Gummiferce. — Trees and shrubs with bi- 

 pinnate leaves, and stipules all or part transformed 

 into spines, sometimes of enormous size ; other- 

 wise unarmed. Flowers in axillary capitula or 

 spikes, fascicled or united into simple or com- 

 pound racemes towards the ends of the branches. 

 Species especially American and African, some 

 Asiatic, few Australian; about fifty in number. 

 (K., Mimos., t. 28, 29. — Jacq., Hort. Schcen- 

 brim., t. 393. — Velloz., Fl. Flum., xi. t. 39. — 

 Koxb., Plant. Command., t. 149, 150, 199. — 

 Delile, Fl. JZgypt., t, 52, fig. 2.— Wigut, 

 Icon., t. 1157. — Nees d'Esenu., Plant. OJJic, 

 n. 332-336.— Bot. Reg., t. 1317.— F. Muell., 

 in Journ. Linn. Soc, iii. 1-17. — Bentii., in 

 Hook. Journ., i. 499; in Lirmaa, xxvi. 629; 

 Fl. Austral., ii. 419.— Bcecii., Trav., ii. 240, 

 t. 6.— K. Mky., Comm., 167.— Haev. & Sond., 

 Fl. Cap., ii. 280.) 



V. Vulgares. — Lofty trees or shrubs, often 

 climbing, American, African or Asiatic, rarely 

 unarmed, usually covered with prickles dissemi- 

 nated over the branches or planted in the pul- 



