Hai Zao

Hai Zao is derived from species of Sargassum, a genus of brown macroalgae in the family Sargassaceae (order Fucales), most commonly Sargassum pallidum and S. fusiforme in Chinese coastal waters. These are not true plants but multicellular brown algae attached to rocky substrates in the intertidal and shallow subtidal zones of the Pacific along the coasts of China, Korea, and Japan. The thallus consists of a discoid or claw-like holdfast, a short cylindrical stipe, and a much-branched frond bearing flattened, leaf-like blades and numerous small, spherical, gas-filled bladders (pneumatocysts) that provide buoyancy. Color ranges from olive-green to yellow-brown owing to chlorophylls masked by fucoxanthin. Reproductive structures called receptacles develop in the upper branches. The species form extensive submerged meadows that provide habitat for marine fauna, and the whole dried thallus is harvested for use.