Journal of the Chemical Society. Journal of Experimental Medicine. Les Sucres, Maquenne, 1900. Manual of Botany, 6th Edition, Gray. Medical and Surgical Reporter. New York Medical Record. Proceedings of the American Pharmaceutical Association. Treatise on Chemistry, Roscoe and Schorlemmer. Ueber Mategerbstoff, Reuchlin (Dissertation) 1904. SOME CONSTITUENTS OF THE POISON IVY PLANT. (RHUS TOXICODENDRON) INTRODUCTION. Plants belonging to the natural order Anacardiaciae (Cashew family or Sumach family) are found in all the temperate climates of the world and quite frequently in semi-tropical climates. Many of these plants play important parts in economic botany, yielding dye-stuffs, tanning material, wax, varnish, and drugs. Several species are poisonous. At least three poisonous species of the genus _Rhus_ are found in the United States. These three are all common and well-known plants, but confusion frequently arises concerning them on account of the different names by which they are known in different localities. For example, poison ivy (_Rhus toxicodendron_ or _Rhus radicans_) probably the best known poisonous plant in America, being found in all the States except those in the extreme West, is often confounded with and popularly called "poison oak." The true poison oak is the _Rhus diversiloba_ of the Western States.[1] The third and most poisonous species of this plant is _Rhus venenata_ or _Rhus vernix_; it is the _Rhus vernicifera_ of Japan, from which Japanese lac is obtained. It is popularly known in the United States as "poison sumach," "poison dogwood" and "poison elder." It grows in swamps from Canada to Florida. As the poison ivy is by far the most common of these plants in the Eastern States, a brief description of it is given here:[2] A shrub climbing by rootlets over rocks, etc., or ascending trees, or sometimes low and erect; leaflets 3, rhombic-ovate, mostly pointed, and rather downy beneath, variously notched, sinuate, or cut-lobed; high climbing plants (_R. radicans_) having usually more entire leaves. It is found in thickets, low grounds, etc. Greenish flowers appear in June. [Illustration: Fig. 1.--Poison ivy (_Rhus radicans_ or _Rhus toxicodendron_). _a_, spray showing aerial rootlets and leaves; _b_, fruit--both one-fourth natural size. (Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of Agriculture.)] [Illustration: Fig. 2.--Poison oak (_Rhus diversiloba_) showing leaves, flowers, and fruit, one-third natural size. (Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of Agriculture.)]