Hylocereus
Hylocereus is the traditional genus name for the climbing, night-blooming cacti grown around the world for their large edible fruit — the dragon fruit, also known as pitaya or pitahaya. Its members are sprawling, vine-like plants with fleshy, three-angled green stems that scramble over rocks and up tree trunks, anchoring themselves with aerial roots. Botanists now largely fold Hylocereus into the closely related genus Selenicereus, but the older name remains firmly rooted in horticulture, the fruit trade and everyday grower conversation.
Description
Plants in the Hylocereus group are among the most un-cactus-like of the family to a newcomer's eye. Rather than a squat globe or column, they form long, jointed, climbing or trailing stems that are typically triangular in cross-section — three prominent, wavy-edged ribs running the length of each segment — though older growth can broaden or become more rounded. The stems are a rich matte green, soft and fleshy, and produce abundant aerial roots along their length that grip bark, rock and trellis alike.
Spines are usually short and inconspicuous, sitting in small areoles along the rib margins. The real spectacle comes at night: mature plants produce enormous, funnel-shaped flowers, often 20 cm or more across, with creamy-white inner petals and greenish or yellowish outer segments. These open for a single night, are heavily fragrant, and are pollinated in the wild by moths and bats — hence the common label "night-blooming cereus" applied loosely to several members. Successful pollination yields the familiar dragon fruit: a rounded berry with a leathery, brightly coloured skin bearing leafy scales, and a white, red or magenta flesh studded with tiny black seeds.
Distribution
The dragon-fruit cacti are native to the tropical and subtropical Americas — Mexico, Central America, the Caribbean and northern South America — where they grow as climbers and epiphytes in seasonally dry forest and scrub, rooting in leaf litter and rock crevices rather than deep soil. Their easygoing nature and valuable fruit have carried them far beyond this range: they are now cultivated commercially across Southeast Asia, Australia, Israel and much of the frost-free tropics and subtropics, and have naturalised in some regions.
Notable species
The following are among the most widely grown members of the traditional genus (many now carry Selenicereus names in current taxonomy):
- Hylocereus undatus — the classic white-fleshed dragon fruit with bright pink-red skin; the most commonly cultivated species.
- Hylocereus costaricensis — a red- to magenta-fleshed pitaya, prized for its deeply coloured fruit.
- Hylocereus polyrhizus — another red-fleshed type widely grown in the fruit trade.
- Hylocereus guatemalensis — a vigorous species often used in breeding and as a parent of commercial hybrids.
The yellow-skinned pitaya usually sold as "yellow dragon fruit" belongs to the closely allied Selenicereus megalanthus.
Cultivation
Hylocereus are some of the most forgiving cacti a beginner can grow, provided their tropical origins are respected. Give them warmth, bright light and something to climb: because they are natural scramblers, they crop best when trained up a sturdy post or trellis, allowing the stems to arch over and flower at the top. Unlike desert cacti, they appreciate a richer, moisture-retentive but still well-drained mix and more regular water during the warm growing season, easing off as temperatures drop.
They are frost-tender and want to stay comfortably above freezing; a light chill can scar the stems, and a hard frost will kill them. Feed lightly through the growing months to fuel their fast, hungry growth. Flowering — and therefore fruit — generally begins only once a plant is a few years old and well established, and many named fruiting cultivars need cross-pollination with a compatible partner, sometimes done by hand at night, to set a good crop. See Repotting for moving on vigorous plants, which can quickly outgrow a small container.
Hobby and cultivar notes
In the hobby, Hylocereus wear two hats. Fruit growers cultivate a large range of named selections and hybrids chosen for flesh colour, sweetness, skin appearance and self-fertility, and propagate them true-to-type from stem cuttings, which root quickly and fruit far sooner than seed-grown plants. Ornamental growers, meanwhile, value the genus as a rootstock: vigorous Hylocereus segments are a popular, fast-growing stock for grafting slow or chlorophyll-free cacti such as the well-known red and yellow Gymnocalycium "moon cactus" grafts. Do note that Hylocereus rootstock is itself cold-sensitive, which limits the hardiness of anything grafted onto it.
Propagation by seed is easy from ripe fruit and useful for breeding, but seedlings are variable and slow to fruit, so cuttings remain the standard for maintaining a known cultivar.
See also
- Selenicereus — the genus into which Hylocereus is now largely merged
- Grafting · Propagation — cuttings · Soil and potting mix · Watering · Repotting