How to Know the Aquatic Plants (The Pictured Key Nature Series)

From Preface: "...The following key to aquatic plant genera was written for those who may not be experienced botanists, but who wish an introduction to plants in the aquatic environment, and to know their names. The genera included in this edition are the most common or more frequently seen in the United States, although in some sections of the country (coastal swamps, the arid southwest and the lower Mississippi valley) there are some genera locally common which are not treated....Each genus is illustrated and for some, more than one species is depicted to help give an idea of the variations within a genus....The distribution range of genera in the United States has been extended following more recent publications on aquatic plants, and a discussion of their ecology has been introduced..."