THE -WATER G. W. PRESCOTT ^ictuned 'Key true*. J J ^HOG* 1930 Gift of Elaine. Gomb&ig VtbtiULOALf, 1984 In Mzmofiy o{$ m Hqji S>u>£qji Judy Joyz o; x; oi=0 5! o CO' m = d 5^ How To Know THE FRESH-WATER ALGAE An illustrated key for identifying the more com- mon Fresh-water Algae to genus, with hundreds of species named and pictured and with numerous aids for their study. by G. W. PRESCOTT, Ph.D. Professor of Botany Michigan State University Wgods Hole Oceanographic Institution Clark Reading Room MARINE BIOLOGICAL LABORATORY LIBRARY WOODS HOLE, MASS W. H. 0. I. WM. G BROWN COMPANY Publishers DUBUQUE, IOWA Copyright 1954 by H. E. Jaques Library of Congress Catalog Card Number: 55-3214 THE PICTURED-KEY NATURE SERIES "How to Know the Insects," Jaques, 1947 "Living Things—How to Know Them," Jaques, 1946 "How to Know the Trees," Jaques, 1946 "Plant Families—How to Know Them," Jaques, 1948 "How to Know the Economic Plants," Jaques, 1948, 1958 "How to Know the Spring Flowers," Cuthbert, 1943, 1949 'How to Know the Mosses and Liverworts," Conard, 1944, 1956 "How to Know the Land Birds," Jaques, 1947 "How to Know the Fall Flowers," Cuthbert, 1948 "How to Know the Immature Insects," Chu, 1949 "How to Know the Protozoa," Jahn, 1949 "How to Know the Mammals," Booth, 1949 "How to Know the Beetles," Jaques, 1951 "How to Know the Spiders," Kaston, 1952 "How to Know the Grasses," Pohl, 1953 "How to Know the Fresh-Water Algae," Prescott, 1954 "How to Know the Western Trees," Baerg, 1955 "How to Know the Seaweeds," Dawson, 1956 "How to Know the Freshwater Fishes," Eddy, 1957 "How to Know the Weeds," Jaques, 1959 "How to Know the Water Birds," Jaques-Ollivier, 1960 "How to Know the Butterflies," Ehrlich, 1961 "How to Know the Eastern Land Snails," Burch, 1962 Other Subjects in Preparation Printed in U.S.A. INTRODUCTION ARDLY any body of water or moist spot on the face of the earth is devoid of algae. They are almost as nearly ubiquitous as are the bacteria which are perhaps the most widely distributed organisms in the world. The variety of form and color exhibited by the algae is seem- ingly endless and Nature has shown no bounds in designing these ornate plants, many of which have bizarre shapes and specialized habits. Because of the bright colors possessed by many algae and because their extensive growths which develop in ponds and streams, algae frequently attract attention. The more conspicuous growths of fresh- water algae are usually referred to erroneously by the stranger as "water moss," "moss," "frog-spittle," or are sometimes called "pond scums." This illustrated key is designed to give the student who is equipped with a microscope an opportunity to explore the world of freshwater algae and to give the correct scientific name (at least the genus name) to the more common forms. The student may find to his surprise that a clot of "moss" will include half a dozen or more distinct and recognizable plants, each with its own individual char- acteristics of form, method of reproduction, and life history. In some collections taken from acid bogs as many as 200 or more different species may be found. It is hoped that this book will be a help in identifying the genera of freshwater algae and that it will serve toward the elimination of the indefinite and erroneous names under which they pass. To be sure, the naming of a plant or an animal is not necessarily an end unto 'itself—but identification and naming must serve as a basis for a study of structure, life history, ecological distribution and economic im- portance. Just as when one knows the name of a person and so can then learn more about him (or her), so the naming of algae can be the beginning of further investigation for the pure pleasure of getting , acquainted with the world of aquatic life about us, or for scientific . pursuits. Having found the generic names of Ireshwater algae, the student » may wish to identify the plants according to their specific names. For this he will want to turn to some of the works listed in the bibliography. An attempt has been made in illustrating the genera of algae to present the most common species that one is likely to meet, or to give illustra- tions of several species of a genus. In many cases, among the one- celled and colonial genera especially, there is considerable variation in form among the species contained in a genus. The student will need to keep this point in mind when matching a plant under con- sideration with the illustrations in the key. A plant in question may be a species somewhat or quite unlike the one shown. The generic names used in the key are those of long-standing and the ones to be found in floras and handbooks the world over. In a few instances the names have been reduced to synonymy by special- literature for long- ists who have critically examined the old taxonomic forgotten synonymies. The advanced student is urged to look into the writings of specialists if he wishes to adopt the recent taxonomic terminologies. East Lansing, Michigan 1, 1954 August Ifl . n>A^o<mr^ ? of We first met Doctor Prescott when he was working on the Algae University. We've had some Iowa as a graduate student at our State < pleasant correspondence through the years since then and now it is a pleasure to include the results of his years of study in our Pictured-Key Nature Series. I H. E. JAQUES Editor CONTENTS Page Introduction U1 What Are Algae 1 The Phyla of Algae 5 Synopsis of Algal Phyla 10 How and Where to Collect Fresh-water Algae 12 Books and Papers Dealing with the Classification of Fresh-water Algae 18 . 20 Pictured-Keys to the More Common Fresh-water Algae . A Check List of the More Common Fresh-water Algae According to Families, Orders and Phyla 189 Index and Pictured-Glossary 199 CHINESE IDIOGRAPH FOR THE WORD ALGAE. WHAT ARE ALGAE LTHOUGH most freshwater algae are microscopic, many kinds are greqarious and occur in such numbers as to form the well-known and conspicuous "pond scums," "water blooms," or "water mosses." A few genera are individually large enough to be seen easily without the aid of a microscope, e.g., the stone-worts (Characeae), or some of the freshwater red algae such as Batiachospermum. If it were possible for freshwater algae to grow as large as some other plants (mosses and ferns for example) and to live upon land, they would be considered highly attractive indeed and would be much cultivated as ornamentals. The symmetry of form and the patterns of ixtemal decorations which many of them possess are not excelled by the larger plants in beauty. The varied shapes of both marine and freshwater algae, coupled with their many colors and hues have made them the subject of observa- tion and wonderment for a long time, especially since the invention of the micro- scope. Indeed, the microsco- pic size of most of the fresh- water algae make them all the more intriguing, and since the early days of the first microscopical club they have been used for pleasur- able observation and specu- lation. It is not the aesthetic quality alone of freshwater algae, of course, which explains the amount of interest shown them. For small though they are. freshwater algae (like some of their micro- scopic kin in the oceans) have their own economic importance. Their relationship to aquatic biology problems of various kinds, their trouble- some contamination of water supplies, and their use in general physi- ological research constitute just a few of the manv aspects which lead to a study of them. Purely scientific problems such as their role in organic evolution, the biology of their reproduction and life his- tories, and their ecology are common subjects of investigation. Al- though much is still to be learned from them, the solution, or at least clarification, of many problems in general biology and physiology have been obtained from studies of algae. At this time, for example, much attention is being given to algae in culture for the study of highly important and practical problems in photosynthesis and the products of algal metabolism. Some genera of unicellular algae are 1 HOW TO KNOW THE FRESH-WATER ALGAE being used for the assay and detection of biologicals (vitamins and growth-promoting or growth-inhibiting substances) in tissue culture work. Some of the research on cancer involves studies in the physi- ology and reproduction of algal cells. I Whatever the interests in freshwater algae may be, the student a who has access to a microscope can find many hours of fascination in a few drops of pond watei. The term "algae," derived from the Latin name for sea-wrack, has come to be applied to all relatively simple marine and fresh- < water vegetation. Actually, of course, many different kinds of organ- isms are included among the plants which lie outside or below the realm of mosses (Bryophytes), the ferns (Pteridophytes), and the seed- HOW TO KNOW THE FRESH-WATER ALGAE SPECIES. A particular kind of plant or animal is called a species. For example, a certain rose, or a particular alga such as a "pond silk," or a particular bird is known as a species and is given an identifying or specific name. Because there is so much (although slight) variation between individuals which are in general very much alike, the limita- tions or precise definition of a species of plant or animal is often difficult to draw and is subject to different interpretations of specialists.