466 



ILLUSTRATIONS OF THE NATCEAL ORDERS. 



usually form sheaths around the stems above the leaves, and for 

 their orthotropous ovules (Fig. 518, 526). Stamens definite, inserted 

 on the petaloid calyx. Fruit achenium-like. Embryo curved, or 

 nearly straight, applied to the outside (rarely in the centre) of 

 starchy albumen (Fig. 606). — Ex. Polygonum, Rumex (Dock, 

 Sorrel), Rheum (Rhubarb). The stems and leaves of Rhubarb 

 and Sorrel are pleasantly acid : while several Polygonums (Knot- 

 weed, Smart-weed, Water Pepper, &c.) are acrid or rubefacient. 

 Tlie farinaceous seeds of P. Fagopyrum (the Buckwheat) are used 

 for food. The roots of most species of Rhubarb are purgative : but 

 it is not yet known what particular species of Tartary yields the 

 genuine officinal article. The Ekiogone^ (a large tribe of the 

 southern and western parts of North America, chiefly west of the 

 Rocky Mountains) are remarkable for their exstipulate leaves and 

 involuci-ate flowers. 



898. Ord. Lauracea; {Laurel Family). Trees or shrubs, with 

 pellucid-punctate alternate leaves, their margins entire. Flowers 

 sometimes polygamo-dioecious. Calyx of four to six somewhat 

 united petaloid sepals, which are imbricated in two series, free 

 from the ovary. Stamens definite, but usually more numerous than 

 the sepals, inserted on the base of the calyx : anthers two- to four- 

 celled, opening by recurved valves ! Fruit a berry or drupe, the 

 pedicel often thickened. Seed with a large almond-like embryo, 



destitute of albumen. — Ex. Laurus, Sassafras, Benzoin. All aro- 

 matic plants, almost evei;y part abounding in warm and stimulant 



FIG. 1112. A stammate, and 1113, a pistillate flower of Sassafras. 1114. A stamen with its 

 glands at the iase : the anthers opening by two sets of valves. 1115. Pistil ; the ovary divid- 

 ed. 1116 Branch in fruit. 1117. Section of the drupe and seed. 



