246 



WEEBS AND USEFUL PLANTS. 



153 



ORDER LI. CONVOLVULA'CE^E. (CONVOLVULUS FAMILY.) 



Mostly trailing or twining lierbs, often with a milky juice ; leaves alternate (in Cuscuta 

 reduced to minute scales) ; flowers regular, hexandrous ; calyx of 5 imbricated persistent 

 sepals; corolla 5-plaited or 5-lobed, twisted or convolute in the bud ; ovary 2-celled (rarely 

 3-celled) with a pair of erect ovules in each cell, the cells sometimes doubled by a false 

 partition between the seeds, so becoming 4-celled ; the embryo large, curved or coiled in a 

 mucilaginous albumen. Fruit a globular 2-6-seeded pod. 



A family containing many showy plants, some of which are cultivated for ornament. 

 The medicinal products, Jalap and Scammoay, are furnished by plants of this order. 



FIG. 157. Common Hounds-tongue (Cynoglossum offlcinale). 158. Portion of the corolla 

 with the scales which close the throat. 159. The fruit, consisting of prickly nutlets adher- 

 ing to the base of the styel. 



