Hylocereus undatus is one of the most unruly species in the entire cactus family. It is a hemi-epiphyte, its fleshy, three-angled, jointed stems clamber over other plants and produce fibrous, aerial roots that cling to any available surface. In their natural habitat support is provided by trees, shrubs and rocks in the dry, open woodland of Central America and northern South America, where the species is thought to have originated. In cultivation dragon fruit distribution is now much wider; being commercially cultivated throughout the Americas, Europe and Asia.
Common names of other members of the genus Hylocereus include orchid cacti, jungle cacti and Queen of the Night. The fruit is commonly called Pitaya or Dragon Fruit and grows up to 10 cm long. The fruit skin varies from bright red, crimson through peach-coloured to yellow with unusual, soft green scales. Within the edible fruit there is a viscous, whitish pulp that is full of small, black seeds. It truly is an exotic and beautiful thing. Unfortunately, the flavour does not live up to its glorious good looks. It has a bland, slightly melon-like taste that at best can be described as 'refreshing'; I would recommend it more for garnish or decoration than for eating for its own sake. The fruit can be used to make juice, wine, liqueur and puree for ice cream, whilst fresh and dried Hylocereus flowers are consumed as a vegetable in Taiwan.
The real stars of the Hylocereus show though are its extraordinary flowers. The buds burst open in summer, and the revealed flowers are true giants of the cactus world; at 25-30 cm long these blooms are the largest in the Cactaceae. The white, scented, bell-shaped flowers open at dusk and last for only one night. The flowers are self sterile and must be cross pollinated by bats or moths in the wild or hand pollinated in cultivation to produce fruit.
For those of you with an adventurous horticultural mind (and a particularly large conservatory) Hylocereus is a relatively easy plant to cultivate, and is readily propagated from both cuttings and seed. Its requirements are the same as for most arid plants. It thrives under bright, frost-free conditions in free draining compost that is kept on the dry side in winter. Hylocereus undatus is well worth the space if you want to see some of the most beautiful blooms the plant world has to offer.
Noble PS 2002. Cacti. Biology and uses. University of California Press.
van Wyk B-E 2005. Food plants of the world: an illustrated guide. Timber Press.
National Geographic 2008. Edible: an illustrated guide to the world's food plants. National Geographic.