98 



BOTANY AND PHARMACOGNOSY. 



as normal constituents of the plant. The nitrogen required by- 

 plants is derived either from nitrogen salts contained in the soil. 



Fig. 63. Ginseng plant (Panax quinqve folium) showing fusiform tuberous root, 

 palmately-compound leaves, and solitary umbel of flowers. 



as nitrates and ammonium salts, or from the free nitrogen of 

 the atmosphere. While most of the higher plants are able to 

 assimilate nitrogen compounds existing in the soil, only the 



