Luffa gourds can be either smooth or ridged.
Luffas are part of the gourd family Cucurbitaceae that also includes gherkins, pumpkins, and watermelons. The most common species is luffa aegyptiaca, which is also known as dish cloth gourd, Egyptian luffa, smooth luffa, and vegetable sponge. This luffa has yellow flowers, vines that can grow up to 25 feet, and gourds that look like zucchini