Phycology is the study of algae, a ubiquitous and extremely important range of species ecologically because of the dependence of other species on their primary production. This third edition of Phycology is designed to serve both as a textbook for a one-semester course and also as a reference on modern concepts in the study of algae. Algae are divided into four natural groups and chapters on each group cover the cytology, morphology, physiology, life cycles, ecology, and systematics, all presented in a manner that can be understood by readers with a basic knowledge of biology. The use of clear, concise drawings, as well as the special emphasis placed on those algae that are commonly covered in phycology courses, and encountered by students in marine and freshwater habitats, has led to the establishment of this book as a classic introductory text suitable for courses throughout the world. This new edition offers a larger, more student-friendly format, along with fully updated reference sections and coverage of hot topics such as toxic algae, ozone depletion, and gene sequencing.