Saccharina japonica

Thallus blade-like, broadly linear, linear-lanceolate, coriaceous, smooth, 2-6(-10) m long, 20-25(-40) cm broad, olive-brown to dark-brown. Stipe cylindrical or slightly compressed at base, flattened above and gradually develops into cuneate base of the blade which become rounded with age. The blade at the base slightly asymmetrical. Percurrent strip (to 5 mm thick) along the middle line of the blade occupy to almost half of the blade width. The blade ruffled on both sides of the strip. Margins thin, entire or undulate. Mucilage ducts present in blade, stipe and rhizoids. Sporangial sori in patches develop on both surfaces of thallus and do not coincide in outline. Attachment by branched rhizoids to rocks, stones, pebbles and shells in low intertidal and subtidal exposed to strong wave action.

Temperate latitudes of the Asian coast of Pacific Ocean.