Ariocarpus bravoanus
| Light | Bright light; a little shade from the fiercest afternoon sun |
|---|---|
| Water | Very sparingly; keep bone-dry through a long winter rest |
| Soil | Extremely free-draining mineral mix, gritty and lean (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11 |
| Propagation | Seed (primary); grafting to speed slow seedlings |
| Toxicity | Not considered edible; see Legal status |
Ariocarpus bravoanus is a recently described, highly sought-after living rock cactus from north-central Mexico, prized by collectors for its rosette of woolly, triangular tubercles and its cerise-pink flowers. It is one of the most coveted members of the genus Ariocarpus, and includes the especially prized subspecies hintonii, which many growers treasure for its neat, tightly packed tubercles.
Description
Ariocarpus bravoanus is a small, slow-growing geophyte that sits low against the ground, with much of its bulk hidden as a stout tuberous root. The visible body is a flattened rosette of firm, triangular tubercles, each tipped with a tuft of pale wool along the upper groove. Like other members of the genus it is spineless, relying instead on its camouflaged, rock-like form for protection — pulling down into the soil during drought so that only the flat crowns show among the surrounding stone and litter.
Flowers appear from the woolly crown in autumn, emerging from the centre of the plant. They are funnel-shaped and a vivid magenta to pink, opening over a few days and giving the otherwise sombre plant a brief, striking display.
The subspecies hintonii (once described as its own species, Ariocarpus hintonii) differs in its more numerous, smaller and more regularly arranged tubercles, forming a denser, more symmetrical rosette. Growers often regard it as the more ornamental of the two forms.
Distribution and habitat
The species is endemic to a limited area of north-central Mexico, in the state of San Luis Potosí; the subspecies hintonii is known from a separate locality within the same region. Plants grow on exposed limestone slopes and gravelly flats in arid scrub, wedged among rock where their flattened bodies are nearly invisible when not in flower.
Wild populations are small, localised and under heavy pressure from illegal collection and habitat disturbance, which is a major reason the plant is so strictly protected (see Legal status below). Nursery-raised, seed-grown plants are, by contrast, entirely legal to own and increasingly available to hobbyists.
Cultivation
Ariocarpus bravoanus is grown much like the other slow-growing Ariocarpus species, and rewards patience above all. Its greatest enemy is excess moisture at the root: the large tuberous root rots readily if kept damp. Use a very lean, sharply draining, mostly mineral mix in a deep pot that accommodates the taproot, and place the plant in bright light with only slight shading from the harshest summer sun.
Water thoroughly only when the soil has dried out completely during the growing season, then allow it to dry again. Through winter keep the plant bone-dry and cool; this dry rest is essential both to prevent rot and to encourage the autumn flowers. Because growth is exceptionally slow, many growers graft seedlings onto a vigorous rootstock to build size quickly, later growing selected plants on their own roots. See Watering and Repotting for general technique.
Propagation
Seed is the standard and usually the only practical method. The fine seed is sown on a warm, mineral surface kept humid until germination, after which seedlings are grown on very cautiously to avoid damping-off. The species rarely offsets, so vegetative increase is uncommon except through grafting of seedlings. See Propagation — seed for a full walkthrough.
Common problems
- Rot — by far the most common cause of loss, almost always from overwatering, a slow-draining mix, or moisture during the winter rest; the tuberous root softens and collapses.
- Etiolation — too little light causes the tubercles to elongate and the rosette to lose its tight, flattened form.
- Pests — root mealybugs are a particular menace on tuberous-rooted species, hiding in the mix around the taproot; red spider mites and ordinary mealybugs may also occur. See Pests and diseases.
Legal status
Ariocarpus bravoanus, like the whole genus Ariocarpus, is listed under CITES Appendix I — the strictest level of international protection, reserved for species threatened with extinction. This tightly restricts international trade in wild-collected plants; artificially propagated, nursery-grown specimens may be traded with the appropriate documentation. The species is also protected under Mexican law, and collection of wild plants is illegal.
Species of Ariocarpus have additionally been reported to contain minor alkaloids, and on that basis the plant may fall under controlled-substance regulations in some jurisdictions. Growers should be aware of both the conservation controls and any local legal restrictions that apply where they live. This article is a horticultural reference only and covers cultivation and conservation; it does not address any other use.
See also
- Ariocarpus — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting
- CITES