– Myrtillocactus geometrizans (2020)
By Pat Mahon (February 2020)
The bilberry cactus, Myrtillocactus geometrizans, is a species worth talking about due to its prolific nature and uses beyond cultivation. It gets its common name from the fruits, which resemble those of a bilberry (European blueberry). The stems of this species have a blue sheen caused by the glaucous nature of the stems.
In time, the blue fades away, and larger specimens will develop woody trunks. These are candelabra-shaped cacti that grow from less than 12 inches to well over 10 feet in height. They are found across Central America.
Before we talk about cultivation, it is interesting to note that the fruits of this cactus are harvested and eaten. Despite the large stature of these cacti, the flowers and fruits are rather small. Flowers are borne at the areoles, and eventually the ovaries swell into blueberrylike fruits. The berries are reported to taste similar to plums with another fruity influence. Plants at only 24 inches tall have the possibility of flowering. The cactus seems to be a species worth trying out for the fruits.
M. geometrizans is commonly cultivated around the world. It is easy to root, fast-growing and very prolific in creating arms. It is adaptable in habitat – plants can be seen growing in Florida and similar tropical areas, into desertlike conditions. In indoor/greenhouse cultivation, the plants are very strong and withstand most conditions thrown at them, as long as the plants remain quite dry during the winter.
A couple of known cultivars are the attractive crested form and the famous Fukurokuryuzinboku … the “boobie cactus.” This highly desired cultivar is an unusual monstrose form that has sagging areoles. At this point, I’m trying to not be funny.
The other major use for this species is in grafting. The thick rootstock of M. geometrizans is quick to root out and gives a generous area for contact of whatever cactus scion you’d like to grow. It is preferred as rootstock over Hylocereus (dragonfruit) species because the compatibility success between the rootstock and scions of unusual cacti is much better in Myrtillocactus.
M. geometrizans is often seen as the rootstock for very large and robust scions of rarer or slower-growing cacti. Hylocereus species can have a smaller area of contact and require more water to survive as a graft. This, in turn, can force fast growth on the scion and cause scarring and infections.
In cultivation, this is a plant with which many people report continued success. There may be even more growers of M. geometrizans than expected, since many grafted cacti utilize that rootstock. I’ve heard comments on the crested form eventually rotting, likely due to the crest growing into the dirt. Consider repotting your crested bilberry cactus once the crest begins to grow into the substrate and utilize a substrate that is drier than the peat-rich soils in which they are commonly sold.
of about 24 inches. Photo by Barbara Dye.
The cultivar Fukurokuryuzinboku is reportedly slow-growing. The normal form is also popular and gorgeous, and can be seen growing well with people across the planet. As mentioned, this species may have the ability to flower at only 24 inches in height. Flowering may occur in spring, while fruits remain on the cactus for a prolonged amount of time. M. geometrizans needs thorough watering during the summer, but must dry out. In winter, the plants should not be watered unless the stem begins to shrivel.
Cuttings of this species are best made during the warmer weather months, as the cuttings only root with heat. Do not water cuttings; they need to be very dry. As younger or smaller plants, they should grow in partial shade. If allowed to grow into larger plants, they can then tolerate full sun.
M. geometrizans is a versatile and useful cactus in the hobby. It is a very “easy” cactus that can be grown by just about anyone, and even allows some to grow “difficult” cacti species that would not tolerate our local conditions.
Sources:
Cactus Art Nursery – https://www.cactus-art.biz/schede/MYRTILLOCACTUS/Myrtillocactus_geometrizans/Myrtillocactus_geometrizans/Myrtillocactus_geometrizans.htm
Wikipedia – https://en.wikipedia.org/wiki/Myrtillocactus_geometrizans
All the Fruit – https://www.youtube.com/watch?v=8MznpmmOxfg