268 Plant Biology 



of the asafetlda plant (Ferula assafoetida) of the parsley family. Asa- 

 fetida is an ill-smelling substance used for medical purposes and some- 

 times used in small quantities as flavoring for sauces and gravies. 



Numerous plants produce gelatinous materials used as medicines them- 

 selves or used in the preparation of medicines. The following will illus- 

 trate a few of this type: 



Gum arable is made principally from the juice of the gum arable tree 

 (Acacia Senegal) of the pulse family. This gum contains a carbohydrate 

 called arabin (C12H22O11) which has the same formula as cane sugar. 

 When arabin is boiled with dilute acid, the sugar, arabinose, is formed. 

 Gum tragacanth is made from the juice of the stem of the tragacanth 

 shrub {Astragalus gummifer) of the pulse family. This gum contains 

 a carbohydrate tragacanthin (C6H10O5). Licorice is secured from the 

 roots of the licorice plant (Glycyrrhiza glabra) of the pulse family. 

 Gelatinous materials are obtained from Irish ''moss" (Chondrus crispus) 

 (Fig. 33) and from Iceland "moss" (Cetraria islandica). 



Certain plants contain various poisonous substances which prove 

 harmful when eaten. The following examples are typical: 



Jimson weed or thorn apple (Datura stramonium) of the nightshade 

 family is quite common around farm buildings. It is sometimes mistaken 

 for other plants and eaten with fatal results. Indian poke (Veratrum 

 viride) of the lily family has been mistaken for other plants and eaten 

 with dangerous results. Common pokeweed (Phytolacca decandra) of 

 the pokeweed family is often eaten like asparagus. Unless the leaves, 

 roots, seeds, and fruits are thoroughly boiled in many changes of water, 

 death may result. Monkshood (Aconitum napellus) of the crowfoot 

 family is common in gardens and has produced fatal results when eaten. 

 Deadly water hemlock (Cicuta maculata) of the parsley family is fre- 

 quently confused with other plants found in swampy regions. Poison 

 hemlock (Conium maculatum) of the parsley family is very common 

 along roadsides and may prove fatal when the seeds, leaves, or roots are 

 eaten. The roots and bark of the elder (Samhucus canadensis) of the 

 honeysuckle family and the locust (Robinia pseudacacia) of the pulse 

 family are sometimes fatal. Every part of the Indian tobacco plant 

 (Lobelia inflata) of the bellflower family, which is common in pastures, 

 is highly poisonous. The wilted leaves and the kernels of the cherry 

 stones of the wild black cherry contain prussic acid, which is very dan- 

 gerous to man and cattle. Sheep laurel (Kalmia augustifolia) and moun- 

 tain laurel (Kalmia latifolia) of the heath family are among the most 



