II. DEFINITIONS AND 

 CLASSIFICATIONS 



A. ALGAE 



Algae are the simplest form of plant life. 30 

 The term "alga,-ae" derives directly from the Latin word meaning 

 "seaweed," 31 but as used today encompasses many additional forms. While 

 the vast majority of algae are characteristically aquatic, some few species 

 have become adapted to growth in soil and even in such exotic habitats 

 as floating icebergs. Some are unicellular, others multicellular, with great 

 variations in cellular structure. They may vary in length from less than 

 one micron for the slimy growths, to hundreds of feet for the giant 

 kelps. 32 



Unlike the higher plants, algae possess no true roots, stems, leaves, 

 or seeds. The basic metabolic processes of nutrition and reproduction 

 are all localized in the individual cell, without the transport system of 

 land plants. The one feature common to all algae is the property of 

 photosynthesis — the utilization of light energy to convert inorganic to 

 organic substances. By this method, algae can convert carbon dioxide, 

 water, nitrogen, and mineral substances into diverse types of proteins, 

 carbohydrates, lipids and sterols, vitamins, and other metabolic com- 

 plexes. 33 - 34 



Algae have been extensively studied during the past sixty years, and 

 over 17,000 species have been described. 35 - 36 Their classification has 

 been varied, unstandardized, and in many instances rather badly confused. 

 For many years, they were simply lumped into four principal groups 

 based on gross coloration: green, brown, red, blue-green. 37 With increased 

 understanding of pigments, of metabolic reactions, and of reproductive 

 mechanisms, algae are today classified into seven main Divisions, each 

 subdivided into Classes, Orders, Families, Genera, and Species 38 - 41 : 



I. Chlorophyta: grass green; unicellular, multicellular, a few 

 macroscopic; cell wall of cellulose and pectins, mostly 

 freshwater, some marine. 

 II. Euglenophyta: grass green; unicellular; motile; lacking a cell 

 wall; largely freshwater. 



