The single cells, colonies, filaments or more complexly structured algae are usually grass-green. Motile cells have usually two or four anterior flagella of equal length. This division includes many distinct evolutionary lineages. The single cells, colonies or filaments are yellow, golden-brown or rarely green. Motile cells usually have two anterior flagella of unequal length.
All cells are motile, usually with two slightly unequal flagella.
Sexual reproduction and motile cells are absent. The single cells are brown or brownish green. The motile cells usually have two flagella inserted in a 'gullet' at the anterior end of the cell, one shorter flagella often non-emergent. The single cells or colonies are blue-green. The motile cells are dorsiventrally symmetrical with two lateral flagella.