File:Interstate medical journal (1919) (14764119905).jpg

Identifier: interstatemedica2619unse (find matches)
Title: Interstate medical journal
Year: 1919 (1910s)
Authors:
Subjects: Medicine
Publisher: St. Louis, : Interstate Medical Journal
Contributing Library: The College of Physicians of Philadelphia Historical Medical Library
Digitizing Sponsor: The College of Physicians of Philadelphia and the National Endowment for the Humanities

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Fig-. 8.—Giant Ragweed. A typical hayfever weed, which replaces the commonragweed in moist localities from the gulf states to Quebec, and west toManitoba, Nebraska, Colorado, and New Mexico. plant and tarweed). As the pollen is not wind-borne and there-fore not in the air, it is not a cause of hayfever. The probability,therefore, is that the resinweed, on account of its prevalence andconspicuousness, was selected in the same manner as the golden Scheppegrell: Harmless Flotvers and Hay fever Weeds 137 rod, which has been so long held responsible for hayfever, whilethe real but insignificant hayfever weeds were unsuspected. PRINCIPAL HAYFEVER WEEDS. Common Ragweed (Ambrosia elatior, Fig. 7). This is the causeof 90 percent of the fall hayfever east of the 100th meridian, andis the principal cause of hayfever in the United States generally.
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Fig1. 9.—Sagebrush. This belongs to the wormwood family, which replaces theragweed as the most common hayfever weed in the Rocky Mountain andPacific states. The plant has all the characteristics of the hayfever weeds, beingextremely common, with insignificant flowers (inflorescence) andwithout odor. The pollen is very irritating to hayfever nostrils,is generated in enormous quantities, and is so light that it will travelseveral miles through the air in a brisk wind (15 to 20 miles perhour). Giant Ragweed (Ambrosia trifida, Fig. 8). This is also a typical 138 INTERSTATE MEDICAL JOURNAL hayfever weed, which replaces the common ragweed in moist locali-ties from the gulf states to Quebec and west to Manitoba, Nebraska,Colorado, and New Mexico. It is called horseweed, bloodweed,and wild hemp. The plant bears no resemblance to the commonragweed, but the pollen, in its hayfever reaction7 and under themicroscope, is identical, except in size, which is about twice that

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