WEEDS AND POISONOUS PLANTS 



337 



FIG. 189. The jimson weed. 

 After Weed. 



devised for dealing with the prob- 

 lems raised by the growth of 

 particular weeds. 



354. Plants Poisonous When 

 Eaten. A rather large number of 

 plants contain substances that 

 render them poisonous in greater 

 or less degree when eaten by 

 human beings. Fortunately, the 

 number of poisonous plants to be found in any one locality 

 is ordinarily comparatively small, and it is easy to become 

 acquainted with all the dangerous ones that are likely to 

 be met. The poisonous plants most commonly confused 

 with harmless ones are perhaps some of the mushrooms 

 (see Chapter VIII, 109). Another poisonous fungus of 

 considerable importance is the ergot, which is parasitic upon 

 rye and other grains and upon some wild grasses. Of the 

 much more numerous poisonous 

 seed plants, it is true in many cases 

 that the same substance which 

 gives the plant its harmful char- 

 acter also makes it valuable, when 

 properly used, as a medicine. To 

 the class of poisonous medicinal 

 plants belong aconite, belladonna, 

 conium (poison hemlock), helle- 

 bore, American false hellebore, 

 henbane, lobelia, pokeweed, and 

 stramonium ("jimson weed"). 



Conium seems to have been the 

 source of the extract which, under 

 the name of "hemlock," was used 

 by the Greeks and Romans for 

 FIG. 190. The poison hem- the punishment of criminals. The 

 lock (conium). After Weed, water hemlocks, belonging to the 



