Hylocereus megalanthus

midnight cactus


Hylocereus megalanthus

(K.Schum. ex Vaupel) Ralf Bauer 2003

pronounced: hy-loh-KER-ee-uss meg-uh-LAN-thuss

(Cactaceae — the cactus family)

synonym — Selenicereus megalanthus

(K.Schum. ex Vaupel) Moran 1953

pronounced: sell-ee-nee-KER-ee-uss meg-uh-LAN-thuss

common names: yellow pitaya, midnight cactus

There is some doubt about the taxonomy of this plant – some authorities attribute the two names to separate species, and others give them as synonyms of the same species. Hylocereus is from the Greek 'υλη (hyle) a forest, and the Latin cereus, a candle, referring to its nocturnal blooming habit. Selenicereus is from the Greek σεληνη (selene), the moon, and the Latin cereus. Megalanthus is from two Greek words, μεγας (megas), great, and ανθος (anthos), a flower.

This is a native of South America, and is an epiphyte. There are many specimens of this large tree-climbing, night-blooming cactus on Magnetic Island. It produces one of the largest flowers within the cactus family, between 30 – 38 cm long. We seldom see it in its full glory, unless we are nocturnal and armed with a strong torch – the flowers are usually high in a tree. 2012 was an exception to this – there was a tremendous flowering in February, with the blooms persisting well into the following morning. Fruits were formed, but fell off the plant before fully developing.

The stems may lie upon the ground, or climb, or hang, and often produce aerial roots. The stems have three ribs, and the margins are slightly undulating. There are sharp spines, and this plant should be handled with care. The flowers are nocturnal and infundibuliform; the pericarpel is ovoid or slightly globose, tubercles are large and flattened, with felt-like and spiny areoles subtended by small bracteoles; the receptacle is elongate, the outer tepals long, green and triangular-acute, the inner tepals long, white and broader. There are numerous stamens in two zones.

The fruit is commercially grown in some countries, particularly Columbia, Nicaragua, Vietnam and Israel. The cacti are grown on trellises or, traditionally, on old tree stumps or living tree posts. As the plants have a high tolerance to sulphurous gases, commercial production in Nicaragua is found on the slopes of the Mount Santiago volcano. Many species of pitaya are self-sterile, and so moths and bats are required to achieve cross-pollination. The period during which individual flowers are open is usually one night only, so effective pollinating agents are essential. Ants have been observed pollinating flowers, and also honey bees; but these are relatively inefficient at achieving pollination and fruit set.

The fruits are brightly coloured (yellow in this case, or red with Hylocereus undatus and Hylocereus costaricensis). The red-fruited cacti have large fruits weighing between 150 and 600 grams, white-fleshed in the former and red-fleshed in the latter, each containing many small edible seeds. The yellow fruits are smaller, with a white pulp and higher sugar levels than the red ones. The fruit is covered with many small clusters of spines, that can be brushed off the fully ripe fruit. Fruit set normally occurs 30 – 50 days after flowering, and 5 or 6 fruit crop cycles are achievable in Nicaragua.
There is some commercial production being developed in Australia, both in Queensland and the Northern Territory. So far, only low fruit yields have been achieved. Two fruiting cycles have been observed in the Brisbane area, one in May and a smaller one in August. In northern Australia, there are often difficulties with fruit set. The main fruiting period comes at a good time for marketing, just after the season for most other tropical fruits is over. If this fruit is to ‘catch on’, a great deal of promotion and education of the public will be necessary. The ‘red dragon fruit’ are now beginning to appear in some north Queensland supermarkets. I have seen shoppers looking warily at them.

Photographs taken in Picnic Bay 2012-2014
Page last updated 15th January 2019