Rhodophyta (Rhodophyta) protoflorideophy-ceae (Protoflorideophy-ceae) red cabbage (Bangiales) red cabbage family (Bangiaceae) purslane genus (Porphyra) of the collective name. Porphyra contains up to 29 ~ 35% of the protein and iodine, a variety of vitamins and inorganic salts, delicious flavor, in addition to food can also be used to treat goiter and lower cholesterol, is an important economic seaweed. It is an important economic seaweed. It is widely distributed all over the world, but mainly in the temperate zone. About 70 species have been found. The number of naturally grown seaweeds is limited, and the production mainly comes from artificial cultivation. Porphyra haitanensis, P. yezoensis and P. tenera are the main cultured species. Nori is known as the "vegetable of the sea". Nori is a bit like leeks, and can be harvested and cut repeatedly after it has grown, the first cut is called the first water, the second cut is called the second water, and so on, in which the first water of nori is also known as the first water seaweed, especially tender, nutritious and rich, but it is more difficult to buy, everyone is to keep their own to eat or to give a gift. The better ones in the supermarket are usually 34-water ones, and the worse ones are 78-water ones. When choosing seaweed, you can carefully distinguish the luster, thickness and so on. Japanese seaweed (nori). Nori genus (Porphyra) marine red algae. The chloroplast consists of a layer of cells embedded in a thin gelatinous layer, and is dark brown, red, or purple in color. Sexual reproductive structures are found at the edge of the thallus. It is found in both the northern and southern hemispheres, grows at the high tide line in the intertidal zone, and grows best in nitrogen-rich water (e.g., near the outlets of sewage drains). Harvested and dried for food, it is consumed more than any other seaweed. It is farmed artificially in eastern countries as an important food. It is used as a main ingredient in soups and as an accompaniment to other foods and meats. In the British Isles, seaweed is baked on bread and tastes like oysters.