Stramenopiles Patterson 1989, emend. Adl et al. 2005
Motile cells typically biciliate, typically with heterokont ciliation: anterior cilium with tripartite mastigonemes in two opposite rows and a posterior usually smooth cilium; tubular mitochondrial cristae; typically 4 microtubular kinetosomal roots.
Most Stramenopiles or heterokonts are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton. The name "heterokont" refers to the type of motile life cycle stage, in which the flagellate cells possess two differently shaped flagella.