170 MEDICINAL AND POISONOUS PLANTS 



Volatile oils form the most important constituent of a 

 number of non-poisonous drugs which we have ah-eady stud- 

 ied in the last chapter as food-adjuncts; namely, lemon, 

 caraway, anise, cardamoms, spearmint, sage, ginger, and 



Fig. 163. — Medicinal Rhubarb (Rhcinn nfficinnlc, Buoliwhoat Famil\-, 

 Polygonacere) ■ Plant in flower. A, flower, entire, enlarsed. />, same, 

 out vcrtieally. C, pistil; d, nectar glands. (BaiUon.) — PiTcnnial 

 herb growing 2 ni. tall; leaves hair,y; flowers greenish; fruit, dr\ , red- 

 dish. Nati\-e lionie. Central Asia. 



hops. The drugs calamus, asafetida, and saffron are the only 

 others of this class whicii call for mention here. Calamus 

 consists of the underground stem of the swe(>t-tlag (Fig. 167). 

 It contains about 1% of a volatih^ oil lo which it owes 



