What is the basis of classification of algae?
The basis of classification of algae includes several key characteristics. The main criteria used are major pigments, stored food, cell wall composition, and flagellar number and position of insertions.
For example, Chlorophyceae (green algae) contain Chlorophyll a and b, store starch, have a cellulose cell wall, and possess 2-8 equal, apical flagella. Phaeophyceae (brown algae) have Chlorophyll a, c and fucoxanthin, store mannitol and laminarin, and have 2 unequal, lateral flagella. Rhodophyceae (red algae) contain Chlorophyll a, d and phycoerythrin, store Floridean starch, and lack flagella. These distinguishing features help classify algae into different classes.
Explanation
The textbook context provides a comprehensive table comparing three classes of algae (Chlorophyceae, Phaeophyceae, and Rhodophyceae) across multiple characteristics. The classification is based on observable features like pigments (which give the algae their common names - green, brown, and red), type of stored food, cell wall composition, and flagellar characteristics. The context also mentions that modern classification uses phylogenetic systems based on evolutionary relationships, along with cytological and chemical information (cytotaxonomy and chemotaxonomy).