Hylocereus is a group of cacti that are native to Mexico and other parts of Central America. It has 14 species of cacti, some of which are epiphytic and some are lithophytic. Some are grown as ornamental plants and some are grown for food. The “Pitahaya,” an epiphytic cactus with edible fruits, is a good example. A plant that grows on the trunk of a tree or another plant is called an epiphyte.
These plants have aerial roots, which are special kinds of roots that can take in water from the humidity in the air and nutrients from the small amounts of soil that get stuck in the cracks of the bark. Hylocereus schomburgkii (also called Cereus schomburgkii) this is exactly the kind of plant. That’s what we’re going to talk about today.
There is still a lively debate whether H. schomburgkii is in fact a separate species or it’s another synonym of Selenicereus monacanthus. We have great doubts about this.
Hylocereus can be found at many different heights, from sea level to almost 3000 meters above sea level. It lives in tropical deciduous forests, thorn scrubs and forests, and along the edges of rivers and streams. The fruits of Hylocereus species that can be eaten, especially H. undatus, have been grown for a long time and are now wild all over the world.
Hylocereus are not like the typical cacti we are used to seeing, which have upright stems in the shape of a candelabra and spines. Instead, they have bright green stems that are triangular and have three prominent ribs with lobed and wavy edges. Most of the time, the stems are thin, long, and hanging. They don’t look like they belong to a cactus at all; they look more like the stems of a vine.
Hylocereus schomburgkii are cacti that can be as short as a few tens of centimeters or as tall as one or two meters. Between the lobes, there are small, not-so-obvious areoles, which are the typical button-shaped, usually white buds of cacti. From these areoles, short, not-so-obvious spines grow.
The very beautiful flowers are another reason why they are so popular as garden plants. The flowers are wider than the stems and have a calyx of many yellowish-green sepals that look like big wigs (the sepals are structures similar to both leaves and petals, which form the calyx, that is the green part at the base of any flower which bears the corolla, namely the part with the petals). They are usually white, but depending on the species, they can be anything from white-yellow to red. Their petals are many and close together. In many species, the flowers only last one night and open at night. Bats do their pollination on their own.
- Stem or trunk: shoots slightly bent, strong green, the present one ca. 2 cm ∅, 3-edged. long-shoots, both ends somewhat tapered, edges long-curved, areoles on elevations, occasionally a small stalk, barely over 1 mm long, horn-colored above. Not thickened at base, brown below.
- Flower: profuse, white, areoles up to 5 cm apart.
- Occurrence: Surinam.
Forster published information about this dragon fruit plant for the first time in 1846, which can’t be taken as a valid date. As the author himself says, it’s just a note because there’s nothing else to say. Schumann talks about the name again in 1898 on page 158. Based on Schumann’s confusing use of “dieser” and “jener,” which is hard to understand even for a German speaker, this could be a young form of some Hylocereus, since he only mentions bristles and not strong spines.
Since he says the plants grow in Guyana and there is no wax on the stems, it could be H. extensus or a type of H. monacanthus that doesn’t have wax (including H. scandens, H. lemairei, H. trinitatensis etc.). But it can’t be said for sure that he had the plant that Forster talked about more than 50 years ago.
In 1846, the name Cereus schomburgkii was just being used. There was never a description that could be used to prove the name. Even Schumann’s comment isn’t a description, as Backeberg tried to make us think in 1959, which just adds to the mystery. Schumann is just pointing out that this name was used for the first time and giving some more information. This is not a Schumann-style description.
Even if Schumann’s description from 1898 is considered to be correct, the name can’t come before the names monacanthus (which dates back to 1845) and extensus (dating from 1828). It should be given up because no one knows what it is.
Tips for growing
Here are some tips on how to grow:
- Pitahaya needs to be in full sun or partial shade, as long as it gets a lot of light all year round. Only if you live in a really hot place should you put it in the shade.
- Dragonfruit likes warm temperatures, but it can live in temperatures around 0oC as long as the soil stays dry.
- Don’t water too much and only water when the soil is totally dry. Water once a week in the spring and summer, once every two months in the fall, and not at all during the winter.
- It’s fine if the soil drains well, and it’s even better if inert materials like pumice, sand, or lapillus are added to it. Since this is a cactus that grows on other plants, you should also add some organic matter to your compost.
- They don’t need to be fertilized very often; mixing fertilizer with the water used to water them once a year is enough.
Most of the time, stem cuttings are used to make more of these cacti. Sowing isn’t often done. If you choose to sow, put the seeds in a compost that drains well and keep the pot at 17-21oC. The seeds will not sprout for at least 15–30 days.
In conclusion, Hylocereus schomburgkii is a fascinating cactus that deserves further study. It is an excellent plant for growing in tropical and subtropical climates and has the potential to be used in horticulture and agriculture. More research is needed to determine the optimal growing conditions for Hylocereus schomburgkii, but it appears to be a promising crop plant.