Ishige foliacea

Thallus flabellate, foliaceous, leathery, erect, shortly stalked, repeatedly dichotomously branched, 5–20 cm high, yellowishbrown, dark olive-brown color to blackish when dried. Branches flat, 0.3–2 cm broad. In transverse section, cortex composed of small, spherical, roundish to widely-oval cells, 6-10 μm across, heavily pigmented. Medulla composed of colorless densely entangled filaments, 9–10 μm diam. Unangia clavate develop from superficial cells of the thallus. Attachment by small discoid holdfast. Growing on rocks and boulders often forming vast belt in the middle to low intertidal zone exposed to strong wave action.

North America. Common in Japan, Korea, Taiwan.