Habitat: Only in the Chihuahua Desert in the USA, between the regions of Texas and New Mexico.
Cultivation: Difficult. Careful to watering, exposure to sunlight direct, substrate well-drained.
Curiosity: This new genus was introduced by Alwin Berger, a botanist, in 1925, who realized that some plants considered part of the genus Ariocarpus actually showed unique characteristics, so much so that they deserved the creation of a new botanical genus.
Roseocactus is a genus belonging to the Cactaceae family. Actually, initially, Roseocactus were considered part of another genus: Ariocarpus. This new genus was introduced by Alwin Berger, a botanist, in 1925, who realized that some plants considered part of the genus Ariocarpus actually showed unique characteristics, so much so that they deserved the creation of a new botanical genus.
Unfortunately Berger failed to convince all botanists: Roseocactus continues to be considered, by some nomenclatures, a synonym of Ariocarpus or, at most, a subgenus of it. We will now touch the cerebral world of botanical debates to try to understand a little bit the differences between these two genres. First of all, let’s talk about Ariocarpus :
We could compare plants of the genus Ariocarpus to oysters: difficult to find but hiding a treasure (their flower). Ariocarpus are in fact small plants which, in nature, camouflage very well within the rocks of the Mexican regions where they come from. In fact, their leaves are not like normal leaves: they look more like hardened and gray scales, so much so that the globular species resemble strange gray pine cones, which we would hardly distinguish from rocks. In botany, these “leaves” are actually called tubercles. These tubercles form spherical rosettes (the pine cones) or flattened in the ground, thornless, sometimes covered with fluff on top. The flattened ones look like spectacular gray lichens that grow flat on the ground, between the rocks, and almost look like moss. A distracted passerby would never distinguish them!
Their root is usually formed by a large bulb, often larger than the visible part.
During flowering, insted, these tiny plants suddenly become spectacular: from the top of the plant sprout one or more large, gorgeous pink or purple flowers.
The fundamental difference noticed by this botanist, Berger, is actually in these little tubercles. According to Berger, by breaking the tubercles of the plants he called Roseocactus, you can find remains of fruit parts and also, perhaps, some seeds, which are absent in those of Ariocarpus. This led him to think that the tubercles of Roseocactus, unlike those of Ariocarpus proper, were somehow involved in the production of flowers and fruits. Moreover the flower, according to Berger, in Roseocactus originates from the fluffy part on the top of the plant, while in Ariocarpus it develops from the junction of the tubercles with the central axis.
Do these differences seem ridiculous to you? Understandable. However, botanical debates are based on these small details: details that sometimes prove to be very important to distinguish one plant from another, and therefore also know how to grow and propagate it.
Both Roseocactus and Ariocarpus are very rare: they are found only in the Chihuahua Desert in the USA, between the regions of Texas and New Mexico. They are threatened and therefore, trade in naturally harvested plants is strictly forbidden. Instead, plants can be artificially propagated outside their habitat.
VARIETY AND TYPES
Due to the uncertainity of botanic classification of Roseocactus, we can mention only one species which is reliably classified as Roseocactus: Roseocactus fissurams. Anyway, try to check out our online store to find out more ones!
TIPS FOR GROWING
Ariocarpus and Roseocactus are considered difficult plants to cultivate, but the attention they require will be largely compensated by the satisfaction they give you. These are our tips:
- Exposure in full sun, with an airy environment. This type of exposure does not stimulate the growth of the plant, which remains very slow, but strengthens it and limits the risk of parasites, to which Ariocarpus are unfortunately very prone.
- The minimum temperature should remain at 6-8 °C, with the plant kept in a very dry environment.
- We recommend a clay soil mixed with gravel. The gravel should not be angular so as not to risk damaging the root.
- It should be watered only when the soil is well dry, but with abundant water: this will avoid that the roots, difficult to reform especially in plants with a few years of age, dry and ruin.
- Even if the plant does not need frequent repotting (as already mentioned, it has a very slow growth), during this operation it is good to be extremely careful not to damage either the main root or the small filamentous roots that branch out from it.
For the propagation we use mostly the seeds. As already said, these plants show a rather slow growth: for this reason, when the new seedling has finished germinating, it may be convenient to graft it on fast growing plants to give it more vigor in a shorter time than normal.