Largest cactus flowers

The largest flowers within the cactus family (Cactaceae) belong to the genus Selenicereus, aka the moonlight cacti, of Mexico, Central America, northern South America and the Caribbean. Its short-lived, often-scented nocturnal blooms can reach more than 30 centimetres (12 inches) in diameter and up to 40 centimetres (1 foot 3 inches) long. The largest flowers of the group are found among what until 2017 were deemed a separate genus known as Hylocereus, including species such as Selenicereus megalanthus, S. undatus, S. grandiflorus and S. escuintlensis.

Moonlight cacti are clambering/sprawling plants that use aerial roots to scramble over rocks, trees and other vegetation, reaching up to 10 m (33 ft) off the ground.

Owing to their nocturnal habit, the blooms of these cacti are most commonly pollinated by moths and occasionally bats.

The former genus Hylocereus is also the source of edible dragonfruit (aka pitaya or pitahaya), the most cultivated being S. undataus.