FAMILIES OF FLOWERING PLANTS 



221 



Fig. 190. The Yellow Gentian {Gentiana flavida Gray). 



Brown, 111. Fl. Northeast. U. S. 



After Britton and 



rated from that family on account of their habit, their basal 'or alternate 

 leaves, and the different position of the corolla-segments in the bud. 

 There are 5 genera and about 35 species, widely distributed. The buck- 

 bean {Menyarithes trifoliafa) is a familiar denizen of our northern bogs ; 

 it has a rather handsome spike of white flowers. Limnanthemum in- 

 cludes a number of floating aquatics with leaves somewhat suggesting 

 those of the water lily, and white or yellow flowers. L. nymjjliaeoides, 

 of Europe, is occasionally cultivated for ornament. 



Family Apocynaceae. Dogbane Family. Consists of herbs shrubs, 

 or in some tropical genera, trees, ^vitli an acrid and usually poisonous 

 milky juice. The leaves are simple, and the flowers regular and o-parted, 

 the corolla often twisted, a fact which led Linnaeus to give the name 

 Contortae to the group. The stamens are equal in number to the co- 

 rolla-lobes, and inserted on the throat alternating with them ; the ovary 

 is superior, 1-celled or with two distinct carpels ; the fruit consists of 

 two follicles, resembling those of milkweeds, or drupaceous. There are 

 about 130 genera and 1,050 species in this widely distributed family. It 

 is most abundantly represented, however, in tropical regions. The dog- 

 banes are an important group, whether considered from the economic 

 or other standpoint. As has been stated, their juice is ordinarily very 

 poisonous ; but in some instances it has medicinal value, while in a few 

 genera ( Vahea and allies) it yields a fair quality of caoutchouc. A num- 

 ber of important fiber plants are also contained in the family; and in a 



