364 BOTANY AND PHARMACOGNOSY. 



The leaves and bark of the cultivated oleander {Nerium Olean- 

 der) contain the glucoside oleandrin, resembling digitalin in its ac- 

 tion ; a fluorescent principle, and probably several other principles. 



Fig. 173. Asdepias tuberosa: A, simple stem with alternate leaves and terminal cymose 

 umbels; B, fruit- branch with a dehiscent follicle; C, large tap root with young shoots. 



The common periwinkle (Vinca minor) contains the principle 

 vincin which is supposed to be a glucoside and which probably 

 occurs in other species of Vinca. 



