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three-lea\'ed maple are drab colored and of no interest to in- 

 sects but produce enormously more pollen than the bright 

 yellow flowers of the Norway maple which are the delight of 

 honey-gathering insects. 



Anemophilous flowers may generally be recognized as such 

 by their lack of attractiveness to insects. Thus the poplars, 

 while closely related to the willows, are entirely anemophilous. 

 Their flowers lack the sweet scent, yellow color and nectar of 

 the willows, and are left severely alone by flower-visiting in- 

 sects, but they produce enormously more pollen. The oaks, 

 elms, birches, and, in fact, most of our forest trees are of this 

 character. It is only among such plants with drab inconspicuous 

 flowers that one need look for the real causes of hayfever. 



It does not necessarily follow that all wind pollinated plants 

 cause hayfever. This characteristic belongs only to relatively few 

 families. Besides those already mentioned the family of the 

 chenopods possess it to a degree; for example. Russian thistle 

 is an important hayfever plant throughout much of the western 

 part of the country. The closely related family of the amaranths 

 also possess it; for example, the western water hemp in Okla- 

 homa and neighboring states. The Knot-weed family possess it 

 to a still lesser degree; for example, cases of hayfever from such 

 wind-pollinated members as the docks have been recorded. On 

 the other hand the cattails are among the most prolific pollen 

 shedders, yet, I believe, no authentic cases of cattail hayfever 

 have been recorded. Pine is the most universally abundant 

 pollen in the atmosphere yet no cases of pine hayfever have ever 

 been recorded. In fact none of the conifers or other gymno- 

 sperms, except Mexican cedar, seem to be capable of producing 

 hayfever in spite of the fact that they are all outstanding prac- 

 titioners of anemophily. Mexican cedar is a curious exception. 

 It grows on the limestone hills of Texas and, flowering in 

 December and January, is said to cause a severe type of winter 

 hayfever in the city of Austin. It is a juniper (Juniperus mexi- 

 cana), yet the several other members of the genus which are 

 common almost throughout North America seem to be harmless 

 to hayfever patients. In order to be a real cause of hayfever 

 pollen must possess three characters: it must be buoyant and 

 easily distributed in the air; it must be abundant; and it must 

 be toxic. 



The Arlington Chemical Co. 

 yonkers, n.y. 



