166 MEDICINAL AND POISONOUS PLANTS 
in the root of the licorice plant (Fig. 162) is a bitter-sweet, 
yellowish compound forming a jelly with water. 
The astringents present in vegetable drugs, or extracted 
from them, are various tannins, significant properties of 
which have already been described in section 57. As ex- 
amples of drugs used more or less for their astringency may 
Fig. 158.—Marshmallow (Althea officinalis, Mallow Family, Malvacee). 
Flowering top. (Baillon.)—A perennial herb about 1 m. tall, downy 
throughout; leaves pale purplish; fruit dry. Native home, Eastern 
Europe. 
here be mentioned the root of rhubarb (Fig. 163) and the 
bark and leaves of witch-hazel (Fig. 164), from both of which 
fluid extracts and other medicinal preparations are obtained. 
As examples of fixed oils much used in medicine for their 
lubricating or soothing effect, there are in common use the 
