MEDICINAL WEEDS OF IOWA 781 



but of mustard on the other hand, ripe seeds, only, are official. 

 The dried leaves of the catnip have market value but no longer 

 are recognized as official. The roots of the dandelion collected in 

 the autumn are listed in the U. S. P. ; the rhizome of quack grass 

 is marketable. In short, if one is to realize any financial profit 

 from his fields of weeds, he must be able to recognize absolutely the 

 weed in question, for poisonous herbs sometimes closely resemble 

 innocuous weeds and a mistake in identification may result serious- 

 ly; he must also know what part of each plant is salable, when it 

 must be collected, whether in the ripe or immature state, and in 

 what form it is preferred by the trade. It is not an occupation to 

 be followed by the careless or ignorant worker. Ignorance is no 

 excuse for offering to the trade a deadly herb in mistake for its 

 harmless relative. When the life of the patient is sacrificed as a 

 result of such a mistake the old saying, that "if it kills it is poi- 

 sonous, if it cures it is the right herb," will hardly suffice as an 

 excuse. 



For the careful gardener, however, who is willing to wait for his 

 herbs to mature one year, two years, or, as with ginseng, seven 

 years, the occupation of growing drug plants offers many induce- 

 ments. 



