Ishige okamurae

Thallus bushy, wiry, cartilaginous, erect, 5–15 cm high, stalked (1–2 cm high) bearing several flabellate branches, dark olive-brown to black when exposed to the air during low tide. Branching irregularly dishotomous, in all directions. Branches subcylindrical, slightly compressed, 1–3 mm broad (broadened below each axil), tapering towards forked apices. In transverse section, cortex composed of peripherical small, cubical cells in compact rows arranged anticlinally and the innermost larger and more spherical cells. Medulla composed of densely entangled colorless filaments. Plurangia clavate scattered on the surface of the thalli. Attachment by small discoid holdfast to rocks in the upper and middle intertidal zone exposed to strong wave action.

China, Korea, Japan, Taiwan.