Purple leaf lettuce is a collective name for the mutualistic algae found in the sea. Red algae, family Rhodophyta. The algal body is membranous and is called a foliar body. It is purple or brownish green. Shape varies with species. Porphyra is a marine red alga. The chloroplast consists of a layer of cells embedded in a thin gelatinous layer, dark brown, red or purple. Purslane fixer disk-shaped, pseudoroot filamentous. Grows on rocks in the intertidal zone of shallow seas. There are many species, mainly striped purslane, altar purslane, sweet purslane and so on. Rich in protein and iodine, phosphorus, calcium and so on. For food and medicinal use. At the same time, purslane can also be used as medicine, with phlegm softening, clearing heat and inducing diuresis, tonifying the kidney and nourishing the heart. Nori is often mistaken for a plant because of its ability to photosynthesize; however, biologists generally agree that it is not a true plant because it does not have true ductal tissues (xylem and phloem), unlike water plants (seagrass).

Purple leaf lettuce, on the other hand, is a collective term for common purple-leaved vegetables. They generally include: purslane, purple-backed asparagus, purple kale, purple eggplant, purple bok choy, purple groundnuts, purple tomatoes, purple cauliflower, purple leaf lettuce, and many more.