This guide describes 590 species, with detailed information on flowering season, related species, range, and habitat. More than 100 plant drawings supplement these descriptions, and more than 200 color photographs show flowers as they appear in the field. Roger Tory Peterson's unique system shows exactly what features to look for to tell one species from another. Peterson Field Guides are designed to work in the field, and every illustration, every word, is directed to that end. For each Field Guide, an author with expertise in the subject and an experienced artist work closely with the editors to ensure that both text and illustrations are accurate.