422 



EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



795. Ord, SaxifragaeeSB (the Saxifrage Family}. Herbs or shrubs, 

 with alternate or opposite leaves. Calyx of four or five more or 

 less united sepals, either free from or more or less adherent to the 

 ovary, persistent. Petals as many as the sepals, rarely wanting. 

 Stamens as many, commonly twice as many, or rarely three or 

 four times as many, as the sepals, perigynous. Ovaries mostly 

 two (sometimes three or four), usually united below and distinct at 

 the summit. Seeds numerous, with a straight embryo in fleshy 

 albumen. There are three principal divisions, or suborders ; 

 namely : 



796. Sllbord, Saxifrages '(the true Saxifrage Family). Herbs. 

 Petals imbricate in aestivation. Capsule (when the carpels are 

 united), either two-celled with the placentae in the axis, or one- 

 celled with parietal placenta. Ex. Saxifraga, Sullivantia (Fig. 

 721), Heuchera. Of little consequence, except as ornamental 

 plants. The roots are generally astringent ; powerfully so in Heu- 

 chera, especially in the common H. Americana (sometimes called 

 Alum-root). 



FIG. 721. Sullivantia Ohionis. 722. Flower with the calyx laid open, somewhat enlarged. 

 723. Fruit surrounded by the persistent calyx and withered petals, enlarged. 724. Section of 

 the lower part of the capsule, magnified; showing the central placenta covered with the as- 

 cending seeds. 725. A magnified seed, with its cellular, wing-like testa. 726. Section of the 

 nucleus, showing the embryo in the midst of albumen. 



