Hylocereus undatus is a lithophytic or hemiepiphytic cactus with creeping, sprawling or clambering stems. It branch profusely. The stems are green, with generally 3 ribs, up to 33 feet (10 m) long, with joints up to 4 feet (1.2 m) long and up to 4.8 inches (12 cm) wide. They climb by use of aerial roots. Margins are horny and undulate with wings that are up to 2 inches (5 cm) wide. The spines on adult branches are 1 to 3, grayish-brown to black in color and up to 1.2 inches (3 cm) long. The scented, nocturnal flowers are greenish-yellow or whitish, rarely rose-tinged with green, up to 14 inches (35 cm) long and up to 12 inches (30 cm) in diameter. The fruit is oblong to oval, up to 5 inches (12.5 cm) long and up to 3.6 inches (9 cm) in diameter.