Poison Oak Small 194×320 Medium 388×640 Large 620×1024 Download Tiff Original 1454×2400 | (648.4 KB) Description Also known as rhus diversiloba. It is a poisonous shrub located on the Pacific coast of North America that causes a rash on contact. Keywords north america, pacific, pacific coast, Poison oak, rash, rhus diversiloba, shrub Galleries Flowers and Shrubs: N-O Source: Government Printing Office Yearbook of the United States Department of Agriculture (Washington, D.C.: Government Printing Office, 1897)