Why is algae no longer classed as a plant?

Answer 1

because algae now is a fungus that grow on TOP of polluted water and does not have any stalks

Answer 2

Algae is no longer classified as a plant because it lacks true roots, stems, and leaves, which are defining characteristics of plants. Algae also have simpler reproductive structures and lack specialized tissues found in plants. Taxonomists have grouped algae into their own distinct kingdom, separate from plants, due to these differences.