Hylocereus undatus


Hylocereus undatus, the white-fleshed pitahaya, is a species of Cactaceae and is the most cultivated species in the genus. It is used both as an ornamental vine and as a fruit crop - the pitahaya or dragon fruit. The native origin of the species has never been resolved.

Common names

Greek "hyle" - wood, matter, Latin "cereus" - waxen, Latin "undatus" - wavy edges of the ribs.

Origin and habitat

Hylocereus undatus is lithophytic or hemiepiphytic. It is widely distributed through the tropics in cultivation. Like all true cacti, the genus originates in the Americas, but the precise origin of the species H. undatus is uncertain and it may be a hybrid. Hylocereus undatus is a sprawling or vining, terrestrial or epiphytic cactus. They climb by use of aerial roots and can reach a height 10 meters or more growing on rocks and trees. The genus is very variable and closely related to Selenicereus.

Systematics

This species is closely related to H. ocamponis and H. escuintlensis.

Description

Dragonfruit stems are scandent, creeping, sprawling or clambering, and branch profusely. There can be 4-7 of them, between 5 and 10 m or longer, with joints from 30–120 cm or longer, and 10–12 cm thick; with generally three ribs; margins are corneous with age, and undulate.
Areoles, that is, the small area bearing spines or hairs on a cactus, are 2 mm across with internodes 1–4 cm. Spines on the adult branches are 1-3, 2–4 mm long, being acicular to almost conical, and grayish brown to black in colour and spreading, with a deep green epidermis.
The scented, nocturnal flowers are 25–30 cm long, 15–17 cm wide with the pericarpel 2.5–5 cm long, about 2.5 cm thick, bracteoles ovate, acute, to 2.5 to less than 4 cm long; receptacle about 3 cm thick, bracteoles are linear-lanceolate, 3–8 cm long; outer tepals lanceolate-linear to linear, acuminate, being 10–15 cm long, 10–15 mm wide and mucronate. Their colour is greenish-yellow or whitish, rarely rose-tinged; inner tepals are lanceolate to oblanceolate, up to 10–15 cm long about 40 mm wide at widest point, and mucronate, unbroken, sharp to acuminate, and white. Stamens 5–10 cm long, are declinate, inserted in one continuous zone from throat to 35 mm above the pericarpel and cream. The style to 17, they are 5-24.5 cm long, stout, 6–8 mm thick, cream, and up to 26 stigma lobes, they can be whole or sometimes split at the top, cream, about 25 mm long. Nectar chambers are 30 mm long.
The fruit is oblong to oval, 6–12 cm long, 4–9 cm thick, red with large bracteoles, with white pulp and edible black seeds.