leguminosae:. 



This, the second largest plant family — being only exceeded by the Composite 

 family — consists of nearly 450 genera, with over 7000 species, and is of much 

 greater economic importance than the latter. 



The Leguminosae family is distributed all over the world, and is only absent 

 from the very remote islands of the Antarctic, though only sparingly repre- 

 sented in New Zealand. 



In regard to the sub-families, the Mimosoideae are entirely absent in Europe, 

 while the Papilionatae are to be found in the Arctic as well as high Alpine re- 

 gions of both hemispheres. 



The family is represented in the Hawaiian Islands by 25 genera, only four 

 of which, however, have arborescent species. 



KEY TO THE GENEEA. 

 SUB-FAM. MIMOSOIDEAE. 



Leaves twice pinnate; flowers in heads or spikes: 



Stamens indefinite; leaves mostly replaced by dilated petioles. . . 1. Acacia 



SUB-FAM. CAESALPINIOIDEAE. 



Leaves twice pinnate: 



Pod-winged along the upper suture, calyx very oblique 2. Mezoneurum 



SUB F AM. PAPILIONATAE. 



Leaves abruptly pinnate: 



Pod four-winged 3. Sophora 



Leaves of three leaflets 4. Erythrina 



ACACIA Willd. 



Flowers hermaphrodite or polygamous; calyx campanulate, toothed or petals free or 

 united; stamens numerous, free or united at the base; ovary sessile or raised, two to many 

 ovuled. Legume oval, oblong or linear, straight or curved, flat or convex, membraneous, 

 coriaceous, indehiscent. Unarmed or thorny trees or shrubs. Leaves bi-pinnate, or re- 

 duced to a phyllodium or dilated petiole. Flowers small, numerous, mostly yellow in 

 globular heads or cylindrical spikes. 



The genus consists of about 450 species, which are distributed over the tropical 

 and subtropical regions of both worlds, being especially numerous in Africa 

 and Australia. In these islands only three species are represented; one is 

 doubtful (Acacia Kauaiensis, libd.). 



KEY TO THE SPECIES. 

 Phyllodia instead of true leaves: 



Pod flat, broad and straight A. Koa 



Pod narrow and curved A. Koaia 



Acacia Koa Gray. 



Koa or Koa ka. 



(Plates 65, 66, 67, 68.) 



ACACIA KOA Gray Bot. U. S. E. E. (1854) 480;— H. Mann Proc. Am. Acad. VII (1866> 

 165; -H. Mann Fl. Haw. Isl. (1867) 235;— Wawra in Flora (1873) 141;— Hbd. Fl. 

 Haw. Isl (1888) 112;— Del Cast. 111. Fl. Ins. Mar. Pac. VI (1890) 160;— Engl.. 

 & Prantl Pflzfam. III. 3 (1894) 110;— Heller PI. Haw. Isl. (1897) 830.— Acacia, 

 heterophylla Hook, et Arn. Voy. Bot. Beech. (1832) 81;— Benth. Mimos. in Hook. 

 Lond. Journ. Bot. L (1839) 368. 



173 



