408 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



five, inserted upon the outside of the disk, valvate in aestivation, 

 sometimes cohering by their tips, and caducous. Stamens as 

 many as the petals, and opposite them ! Ovary two-celled, with 

 two erect ovules in each cell. Fruit a berry. Seeds with a bony 

 testa, and a small embryo in hard albumen. Ex. Vitis (the 

 Vine), Ampelopsis (the Virginia Creeper). The fruit of the Vine 

 is the only important product of the order. The acid of the grape, 

 which also pervades the young shoots and leaves, is chiefly the 

 tartaric. Grape-sugar is very distinct from cane-sugar, and the 

 only kind that can long exist in connection with acids. The sym- 

 metry of the flower is spoken of on p. 269. 



766. Ord, Polygalaceffi (the Milkwort Family). Herbs or shrubby 

 plants, with simple entire leaves, destitute of stipules ; Jhe roots 

 sometimes with a milky juice. Pedicels with three bracts. Flow- 

 ers perfect, unsymmetrical, and irregular, falsely papilionaceous. 

 Calyx of five irregular sepals ; the odd one superior, the two inner 

 (wings) larger, and usually petaloid. Petals usually three, inserted 



672 671 



on the receptacle, more or less united ; the anterior (keel) larger 



FIG. 670. Polygala paucifolia. 671. A flower, enlarged. 672. The calyx displayed. 673. The 

 corolla and stamineal tube laid open. 674. The pistil and the free portion of the stamens. 

 675. Vertical section of the ovary. 676. Vertical section of the seed, showing the large em- 

 bryo and scanty albumen. 



