EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



411 



forming two samaras, and an embryo with long and thin, variously 

 curved or coiled cotyledons (Fig. 103-105); otherwise nearly as 

 in the true Sapindaceae. — Ex. Acer, the Maple ; useful timber-trees 

 of northern temperate regions. Sugar is yielded by the vernal sap 

 of Acer saccharinum, and in less quantity by all the species. 



802. Ord. PolygalaceSC. Herbs or shrubby plants, with simple 

 entire leaves, destitute of stipules. Flowers perfect, unsymmetrical, 

 and irregular, somewhat papilionaceous in appearance, but of wide- 

 ly different structure. Calyx of five irregular sepals ; the odd one 

 superior, the two inner (wings) larger, and usually petaloid. Petals 

 usually three, inserted on the receptacle, more or less united ; the 

 anterior (keel) larger than the rest. Stamens six to eight, combined 

 in a tube, which is split on the upper side, and united below with 

 the claws of the petals : anthers innate, mostly one-celled, opening 

 by a pore at the apex. Ovary compound, two-celled, with a single 

 suspended ovule in each cell : style curved and often hooded. 



Capsule flattened. Seeds usually with a cai'uncle. Embryo straight, 

 large, in fleshy, thin albumen. — Ex. Polygala is the principal genus 

 of the order. The plants yield a bitter principle with some acrid 



FIG 789. Polrgala paucifolia. 790. A flower, enlarged. 791 The calyx displayed. 792 

 Tim corolla and sramineal tube laid open. 793 The pistil and the free portion of the stamens. 

 791 Vertical section of the ovary. 795 Vertical section of the seed, showing the large embryo 

 and scanty albumen. 



