Fake longan is generally the imitation of mad fruit, and the two are very similar. The method of distinguishing them is as follows: 1. Longan (1) has a flat shell, and a few of them are inconspicuous scales. There is a small "bud" next to the pedicel, and there are lines around the pedicel. (2) The inner wall of the shell is brown, smooth and shiny. (3) The pulp does not stick to hands and is easy to peel off, and the pulp is a little transparent and tough. The pulp completely covers the seeds. (4) The stone is round and smooth, and there is no grain. After the stone is cut, the brown-black shell and seed are easy to separate. (5) The pulp has the unique sweet smell of longan. 2. The shell of Mad Man Fruit (1) is generally coated with yellow powder, with no pedicel and small "buds" and no grain, and the shell has obvious scaly protrusions, much like litchi. (2) The inner wall of the shell is pale or yellowish, uneven and dull. (3) The pulp is not easy to peel when it sticks to hands, and the peeled pulp has no toughness. The pulp does not completely cover the seeds. (4) The stone is oval, with an obvious ditch and groove. After cutting, the brown husk and seed are not easy to separate. (5) There is no fragrance of longan, only a little bitter sweetness.