Why aren algae in the plant kingdom?
Algae do not develop from a multicellular embryo into a more complex form like plants. They retain a very simple form when mature even if multicellular. Algae develop no specialized tissues that support or transport fluids. Algae have no roots stems or leaves. The cell wall chemistry contains different components like agar or alginic acids mixed with cellulose and the the form of food reserves in cells differ from that of plants. Algal plastids do not differentiate into many types as plant plastids do. Algal plastids contain pyrenoids to fix CO2 into starch. These are specialized membrane bound protein functions within the algae’s plastids. Plant plastids have diverged into specialized functions such as amyloplasts to store starch. Plants can be aquatic like the flowering plant Wolffia borealis and show all the specialized development of a plant. It has flowers and emergent floating leaves. Aquatic plants can obtain nutrients from both their substrate and the water they live in. Plants
