To sum up, watermelon and loofah are different. Watermelon is short and thick in shape, smooth in surface and not easy to break. Luffa is slender, easily broken and has a rough surface.
According to the data:
The daily "Luffa" in some parts of South China, that is, the Luffa with prominent edges and corners, is actually called "Guangdong Luffa" or "Ribbed Luffa" in the scientific community; However, the variety with inconspicuous skin edges and corners, which we call "watermelon", is actually a "loofah" in the scientific field.
As a common vegetable variety in South China, especially in Guangdong, this kind of "rib loofah" has grown into this strange shape, not a special-shaped loofah variety. It is rare in the northern vegetable market, but it is common in the south. That is to say, outside Guangdong, the loofah people say is actually watermelon, but it is the loofah we often say, which is a rare variety.
Luffa originated in Asia and probably came from India. China has a long history of cultivation, and even has wild distribution in Yunnan and Guangxi. However, the Latin scientific name Luffa aegyptiaca means "Egyptian" because European botanists first introduced this crop from Egypt in the16th century.