Aporocactus flagelliformis, synonymously known as Disocactus flagelliformis and commonly known as the rattail cactus or rats tail cactus is a showy cactus native to southwestern Mexico and parts of Central America. It is distinctive for its long, trailing stems, which grow to about 1 meter at maturity and give the plant its nickname.

Rats tail cactus flowers in spring and early summer, and its blooms are usually violet-red; however, the plant will sometimes grow flowers in idiosyncratic colours like pink and orange. Its flowers are tubular and fairly large, about 5cm wide. Though it produces quite a few flowers during its bloom in the late spring, each flower only lives for a couple of days at most. In the wild Aporacactus flagelliformis is either lithophytic or epiphytic, meaning it grows on the ground or on larger structures like trees. In cultivation, it is usually grown in hanging pots or baskets because of its trailing stems, which can grow up to 30cm in length per year.