Xanthophyta

Abstract

Commonly known as yellow-green algae, the Xanthophyta include one Class, Xanthophyceae, characterized by the following general features: (1) the photosynthetic pigments consist of chlorophyll-a and -e, β carotene and xanthophylls; of these, β carotene is usually present in fairly high concentrations; (2) the food reserves are oil, lipid, and a glucose polymer termed leucosin or chrysolaminarin; (3) the cell walls when present are generally composed of two equal or overlapping halves, e.g., Tribonema (Fig. 7-1) and are composed mainly of pectic substances with smaller amounts of cellulose; in some members the cell walls may be silicified; and (4) the flagellated cells possess two anteriorly inserted flagella of unequal length, the longer being pantonematic and the shorter acronematic.