Leguminosae. 



133 



AOACIA. 



(Family Leguminosae). 



Tender shrubs or small trees, 

 usually with stipular spines or 

 with strong prickles away from 

 the nodes: more or less ever- 

 green. Twigs slender, zig-zag, 

 somewhat angular: pith small, 

 roundish, continuous. Buds soli- 

 tary, sessile, small, usually quick- 

 ly developing into short spurs 

 covered by leaves or their bases 

 and sometimes bristling with 

 pungent stipules, the end-bud 

 lacking. Leaf - scars alternate, 

 small, elliptical, somewhat raised: 

 bundle-trace 1: stipules sometimes 

 present as strong sometimes 

 greatly enlarged spines, which in 

 many tropical species are inhab- 

 ited by pugnacious ants. An ac- 

 count of these (contributed by 

 Safford) is to be found under the 



caption bull-horn in the Standard Cyclopedia of Horticulture. 



Leaves, if present, bipinnate (in Australian species reduced 



to their dilated vertical petioles or phyllodia). 



1. Unarmed: stems very angular, hairy. A. filicina. 

 Armed with pungent stipules or prickles. 2. 



2. Stipules strong and pungent. 3. 



Stipules weak: stems with strong hooked prickles. 4. 



3. Spines short or swollen. (1). A. Farnesiana. 

 Spines becoming long (3-4 cm.) and slender. A. constricta. 



4. Twigs brown: leaflets 3X10 mm. (2). A. Roemeriana. 

 Twigs becoming gray: leaflets small (2x5 mm.). 



(Texas Mimosa). A. Greggii. 



