The motile spores and male gametes are typically diflagellated. This is the only class in the Phaeophyta, so it shares the same characteristics as the division. The sporophyte is the dominant field phase and is made up of a holdfast, stipe, and one or more blades. Gametophyte thalli are not known to exist in nature. Unlike most algae, the Laminariales have tissues that are differentiated into an epidermis, cortex, and medulla.
Growth occurs by means of an intercalary meristem usually between the stipe and the blade.
Plurilocular gametangia consists of a female oogonium which produces a single, non-motile egg and the male antheridia. Meristematic growth produces lateral blades along the stipe or on a terminal blade. The blade is undivided and may or may not contain a central thickened area. Sporangia are only on sporophylls. The stipe is flattened, irregularly branched at the base, and leads to a rachis with papillae.