. It occurs in various parts of nearly all classes of plant, usually in relatively small percentages, and is frequently associated with other substances, such as tannins and alkaloids. Mucilage in plants is thought to aid in water storage and seed germination, and to act as a membrane thickener and food reserve. Among the richest sources are cacti (and other succulents) and flax seeds. Mucilage has a unique purpose in some carnivorous plants. The plant genera Drosera (Sundews), Pinguicula, and… (More on Mucilage)