Hai Dai

Hai Dai refers to Laminaria japonica, the Japanese kelp, a large brown macroalga in the family Laminariaceae (kingdom Chromista, division Phaeophyceae) rather than a true plant. The thallus is divided into a holdfast of branching haptera that anchors it to rocky substrate, a stipe-like stalk, and a single, large, leathery, ribbon-shaped blade that may reach 2 to 6 metres in length and 20 to 50 centimetres in width. The blade is olive-brown to dark brown when fresh, drying to a darker hue dusted with white mannitol crystals. The species grows in cold, well-oxygenated subtidal waters of the northwestern Pacific along the coasts of Japan, Korea, and northeastern China, and is also extensively cultivated by long-line aquaculture for both food and medicinal use.