Hay-fever Plants

Abstract

FOR a plant to be an important cause of hay-fever it must shed its pollen freely, must produce large amounts of pollen, must grow in great abundance, and must have active allergens in the pollen grains. Most wind-pollinated plants satisfy the first condition, but anemophily and entomophily offer little guide to the second. Relative abundance is of immense importance as a distinguishing factor between species of great and small importance in hay-fever; thus only about thirty-five species of grasses out of the thousand or so in the North American flora are important hay-fever plants. Lastly, the allergic qualities of species also differ widely, appearing with fair constancy in the following families: Grarnineae, Compositeae, Chenopodiaceae, Amar-anthaceae, Plantaginaceae, Polygonaceae, Betulaceae, Fagaceae, Ulmaceae, Moraceae, Juglandaceae, Salicaceae, Aceraceae and Oleaceae. Hay-fever Plants Their Appearance, Distribution, Time of Flowering and their Role in Hay-fever, with special reference to North America. (Plant Science Book, Vol. 15.) By Roger P. Wodehouse. Pp. xxvi + 245. (Waltham, Mass.:Chronica Botanica Co.; London: Wm. Dawson and Sons, Ltd., 1945.) 4.75 dollars.