FAMILIES OF FLOWEEING PLANTS. 



243 



almost entirely tropical group con- 

 tains about 355 genera and 5500 

 species of wide distribution. They 

 are herbs, shrubs or trees, with a 4-5- 

 lobed calyx and corolla of varying 

 shape. The ovary is 1-10-celled, be- 

 coming in fruit a capsule, berry or 

 drupe. Rubiaceous plants may usu- 

 ally be recognized by the stipules or 

 leaf-like membranes uniting the 

 bases of the opposite or whorled 

 leaves. The family is of great 

 economic importance, containing, as 

 it does, beverage, dye and medicinal 

 plants, not to mention those of orna- 

 mental value. In the tribe Cincho- ^'^- "°- "^he common plantain (Plan/ago 



. major). After Britton and Brown, 111. Fl. 



neae, for example, is found the genus Northeast u. s. 



Cinchona, which consists of evergreen trees growing chiefly in the val- 

 leys of the Andes of Peru. Several species yield what is known com- 

 mercially as Peruvian bark, and it is from this that quinine and the 

 related alkaloids are obtained. These barks have different properties 

 according to the relative proportions of the alkaloid they contain ; but in 

 all cases the extract is extremely bitter and possesses prominent tonic 

 qualities. 



The same group contains Bouvardia, a genus of handsome green- 



FiG. 211. 



The Partridge-berry {Mitchella repens). After Britton and 

 Brown, 111. Fl. Northeast U. S. 



house shrubs, one species of which {B. triphylla) is native in our south- 



