Weeds of North America

Weeds of North America is possibly the most comprehensive guide available for quick identification of weedy species found in the US, Canada, and Mexico. It exceeds in scope the 350 species described in the Western Society of Weed Science publication, Weeds of the West, which has been a staple for identification of major weed species for many years. In comparison, in Weeds of North America, Dickinson and Royer list 500 species that range from those with minimal potential for acting as weeds to those that are highly invasive. Critical information on each weed species is given in the newer guide, including both a complete description of taxonomic characteristics and a short list of features that can be used for prompt identification. The inclusion of high-quality color photos of various life stages of each plant should be particularly beneficial to people who are not botanically oriented and who are not used to taxonomic keys.

Perhaps the greatest innovation of Weeds of North America is its alternative system for keying out specific weed species. For identification purposes, the guide relies on a relatively simplistic system that identifies species according to major characteristics such as plant type, leaf arrangement, and flower color. There is a potential for misunderstanding the taxonomic key, however, as happened to this non-intuitive reviewer. Color tabs used in the key to categorize flower color are independent of the colors used on the face plates and banners associated with individual plant families (although some colors are used for both the key and certain plant families). The disconnect in color usage between the taxonomic key and the plant families is not immediately discernible, leading one to thumb through the plant families based on tab colors found in the key. A fuller description in the guide’s introductory chapter of how the classification system is supposed to work relative to the plant family section would be beneficial in future editions.