- DIVISION: Tracheophyta
- CLASS: Magnoliopsida (dicotyledons)
- ORDER: Caryophyllales
- FAMILY: Cactaceae
- GENUS: Hylocereus and Stenocereus
There is some taxonomic confusion about exactly what a “dragonfruit” is. For most of us who purchase the fruit at a supermarket or a juice bar, the term most often refers to the plump, juicy fruit of Hylocereus undatus, a vining cactus native to Central America. It’s widely cultivated around the world, especially in Southeast Asia, where it acquired the “dragonfruit” moniker. But the term can also refer to the fruit of any of the other 20 or so species of Hylocereus. In Central America, where they are native, these fruits are known as pitahaya. To make matters more confusing, a completely different genus of cactus, Stenocereus produces similar fruits known as pitaya. Among the best known of these are the organ pipe cactus S. thurberi, which yields pitayadulce (“sweet pitaya”), and S. gummosus, which produces pitaya agria (“sour pitaya”).
Although they are members of the cactus family, Hylocereus species all grow like vines, climbing, clambering, crawling, and sprawling as far as 30 feet (9 meters). Most take root in the soil and climb into trees, but some grow as epiphytes (on other plants). Their thick smooth stems branch frequently. A stem is deeply angled, with three wavy ribs and spines that are few and short. In contrast, Stenocereus species grow in thick, tree- or shrub-size columns. Their cylindrical stems are often ribbed, and are armed with spines.
Both Hylocereus and Stenocereus flower at night, with large blooms arising from stem margins, along the edges of ribs. A flower lasts less than 24 hours; in fact, most close and wilt before dawn, relying on nocturnal pollinators such as bats and moths. Only a pollinated flower yields a dragonfruit (or pitahaya, or pitaya), a fleshy berry with leathery, scaled skin. In most species, fruit ripens to a dark pink, but H. megalanthus bears yellow-skinned fruit. Inside, a multitude of tiny seeds dot the bright pink, white, red, or yellow pulp. Large dragonfruits can weigh almost 2 pounds (900 grams), but most are less than a pound (450 grams).
Though native to the Americas, dragonfruit has long been cultivated in parts of Southeast Asia, and today cultivation has spread across the globe, from Nicaragua, Colombia, and Ecuador to South Africa, Australia, Spain, Israel, and the US, among other places. Hylocereus plants grow quickly, and due to their sprawling, vining habit, must be trellised and tied. The mild, sweet fruit can be peeled and eaten raw (seeds included), or processed into juice, jam, syrup, candy, pastries, and even wine.
If pitaya, or dragonfruit, makes your mouth water, don’t feel guilty. The fruits available in most of the world are cultivated, mostly the wide-ranging H. undatus. But while commercially grown dragonfruit is not threatened, some of the other species of Hylocereus and Stenocereus are. IUCN lists four threatened Hylocereus species, all in Central America, where the chief threat is agricultural expansion. Five species of Stenocereus are listed as threatened: four from Mexico and one in Colombia. Only one of these, S chrysocarpus is threatened by the local collection of fruits; expanding agriculture and cattle grazing are the main threats to other four species. The most endangered pitaya of all? It may be Mexico’s S. chacalapensis, known locally as pitayo gigante. Fewer than 50 mature plants survive, with no signs of regeneration.
CITES lists all Hylocereus and Stenocereus cactuses on Appendix 2: “species not necessarily threatened with extinction, but in which trade must be controlled in order to avoid utilization incompatible with their survival.”