482 BEGOKIACE.E LAURACE^E. 



yellow-coloured principle called rhabarberin, which seems to be 

 identical with chrysophanic acid. Raphides form from 35 to 40 per 

 cent, of Turkey rhubarb, and give rise to its grittiness. These crystals 

 are less abundant in the other varieties of rhubarb. Rhubarb is 

 employed medicinally as a cathartic, astringent, and tonic, in the form 

 of powder, pill, extract, tincture, wine, and infusion. Coccoloba 

 uvifera, Sea-side-grape, so called from the appearance of its fruit, 

 yields an astringent substance, called Jamaica Kino. 



992. Order 149. Begtmiaceie, the Begonia Family. (Apet. Diclin.) 

 Flowers unisexual Perianth coloured, having usually 4 divisions in 

 the male flowers, and 5 or 8 in the female, some being smaller than 

 others ; activation imbricate. Stamens 00, distinct, or united into a 

 solid column ; anthers collected in a head, dithecal, with a thick 

 connective, and longitudinal dehiscence. Ovary adherent to the tube 

 of the perianth, winged, 3-celled, with three placentas meeting in the 

 axis; ovules 00, anatropal; stigmas 3, sessile, 2-lobed, somewhat 

 spirally twisted. Fruit a membranous, triangular, winged capsule, 

 dehiscing below in a loculicidal manner. Seeds 00, minute ; testa 

 thin and reticulated ; albumen ; embryo oblong ; radicle next the 

 hilum. Semi-succulent herbaceous plants and undershrubs, with 

 alternate obh'que leaves, having large scarious stipules. They are 

 sometimes called Elephant's -ear, from the form of the leaves. They 

 are natives of warm countries, as the East and West Indies, and South 

 America. The stomata on the lower side of the leaves of many of the 

 species of Begonia are arranged in clusters, and exhibit a beautiful 

 appearance under the microscope. Their leaves and young stems are 

 acid, and have been used for tarts. Their roots are astringent and 

 slightly bitter. Begonia obliqua is said to have purgative roots, and it 

 is sometimes called wild rhubarb. There are 3 genera, and 159 

 known species. Example Begonia. 



993. Order 150. i.anracete, the Laurel Family. (Apet. Perigyn.) 

 Perianth with 4 or 6 divisions, which are usually in 2 rows (figs. 

 691, 692), the limb sometimes obsolete; aestivation imbricate (fig. 692). 

 Stamens perigynous, definite, often twice as many as the divisions of 

 the perianth, and arranged usually in two rows ; those of the inner 

 row (often three) being frequently sterile (staminodia), (fig. 693 e s). 

 while those of the outer (often six in number) are fertile (figs. 692, 

 693 ef); if the inner stamens are fertile, they are extrorse, while the 

 outer are introrse ; filaments of the inner row often with glands at 

 their base (figs. 325, 694 g] ; anthers 2-4-celled, cells opening by 

 longitudinal valves (figs. 325, 695). Ovary superior, unilocular, (fig. 

 693 0); ovule solitary, pendulous (fig. 693); style simple; stigma ob- 

 tuse (fig. 693 s). Fruit baccate or drupaceous, naked, or covered by the 

 enlarged perianth (fig. 696); peduncle of the fruit sometimes becom- 

 ing fleshy. Seed solitary, pendulous; albumen 0; embryo inverted 



