Acacia 



LEGUMINOS^ 



137 



§ 20. Parts of the flower in 5's or 4's. Flowers in globular 

 heads, or in spikes (in A. suma). Stamens numerous, 

 distinct or only slightly united at the base. Pollen 

 granules in 2-6 masses in each cell. 



44. ACACIA WiUd. 



Trees or shrubs, with or without prickles or spines. Leaflets 

 generally small (less than 1 cm. L, but to 1 • 4 cm. in A. rugata), 

 in numerous pairs, generally with a gland on the petiole. Stipules 

 spiny or inconspicuous. Flowers in globular heads or cylindrical 

 spikes. Peduncles axillary, solitary or clustered, or paniculate 

 at the apex of branches. Flowers small, hermaphrodite or poly- 

 gamous ; floral parts in 5's or 4's. Calyx campanulate, toothed, 

 lobed, or divided into distinct sepals. Stamens numerous, free 

 or slightly united at the base, exserted ; anthers small ; pollen 

 aggregated in 2-6 masses in each cell. Pod compressed, rarely 

 ^'ylindrical, 2-valved or not opening. 



Species 450, widely dispersed through the warmer regions of 

 the world, especially numerous in Australia and Africa. 



§ 1. Stipules spiny, otherwise without spines or prickles. 

 Flowers in globular heads. 

 Involucel close under flower-heads. 



Leaflets in 20-30 pairs, 2-3 mm. 1 1, A. lutea. 



Leaflets in 10-20 pairs, 4-5 mm. 1. 



Pod velvety, obscurely veined, 8-14 cm. 1., 7-8 



mm. br 2. A. torttiosa. 



[Pod glabrous, with longitudinal lines, 4-7 cm. 1., 



8-15 mm. br A. farnesiana.l 



[Involucel about middle of peduncle A. nilotica.] 



§ 2. Stipules not spiny ; prickles in pairs below the 

 stipules, or scattered. 

 [Prickles in pairs below the stipules. Flowers in 



spikes A. suma.'} 



Prickles scattered. Flowers in globular heads. 



Pod velvety, glaucous 3. A. riparia. 



[Pod glabrous, constricted between the seeds A. rtigata.} 



§ 3. Without spines or prickles. Flowers in short 



spikes or oblong heads 4. A. villosa. 



§ 1 . Shrubs or trees, stipules some or all spiny, otherwise with- 

 out prickles or spines. Flower-heads globular ; peduncles 

 axillary, solitary or in a small cluster, or subracemose at 

 the ends of the branches. Pod thick, swollen or rarely 

 flat, not or scarcely splitting open, with a spongy pulp 

 separating the seeds. 



A. Involucel of bracts close under the flower-head. 



1. A. lutea Hitchcock in Bep. Miss. Bot. Gard. (1893) 83; 

 pinnae in 40-10 (60-8) pairs ; leaflets in 20-30 (15-40) pairs, 



