Hylocereus megalanthus

Hylocereus megalanthus is a cactus species native to northern South America, where it is known, along with its fruit, by the name of Pitahaya. The species is grown commercially for its fruit, but is also an impressive ornamental vine with perhaps the largest flowers of all cacti.

Stems may lie along the ground (procumbent), climb (scandent), or hang (pendent). Stems are often only 1.5 cm thick, producing areoal roots; 3 ribs; margins slightly undulating; white areoles; 1-3 spines 2-3 mm long, yellowish; several hairs on young growth, britle-like; green epidermis. Flowers are nocturnal and funnel-shaped, 32-38 cm long; pericarpel is ovoid or slightly globose, tubercles are large and flattened, with felt-like and spiny areoles subtended by small bracteoles; receptacle elongate; outer tepals long, green, triangular-acute; inner tepals 100 cm long, 3.5 cm wide, white, broader; stamens numerous inserted in two zones, yellow; style yellow, stigma lobes numerous, green. Fruit: ovoid, tuberculate, spiny, yellow (or sometimes red?), seeds black; interior edible, having a pleasant, mildly sweet flavor.

Cultivation
An easily cultivated, fast growing plant. Needs a compost containing plenty of humus and sufficient moisture in summer. Should not be kept under 8ºC (46,5ºF) in winter. Can be grown in semi-shade, but best in full sunlight. Extra light in the early spring will stimulate budding. Flowers in June to October. This plant may grow to a very large size.

Source: http://en.wikipedia.org/wiki/Hylocereus_megalanthus
See Also: florists CA, gift baskets, China flowers