Turbinicarpus
Turbinicarpus is a genus of very small, tuberous-rooted cacti from the dry uplands of northern and central Mexico, cherished by collectors far out of proportion to their size for the astonishing variety of their spines — papery, corky, twisted, hooked or all but absent depending on the species. Every member of the genus is listed under CITES Appendix I, the strictest level of protection, reflecting how heavily wild populations have suffered from illegal collecting. A 2022 taxonomic treatment folds the whole genus into Pelecyphora, so both names are in current use.
Description
Turbinicarpus are dwarfs of the cactus world. Most form solitary, flattened-globular to short-cylindrical bodies only a few centimetres across, though a handful clump with age. The stems are divided into low tubercles rather than continuous ribs, and it is the spination on top of these tubercles that gives the genus its charm and its diversity: some species carry soft, flexible, paper-thin spines that can be flattened against the body; others bear corky, twisting spines, fine bristles, or hooked centrals, while a few are nearly naked.
Beneath the soil sits a swollen, often carrot-like taproot that can be as large as the visible plant. This tuberous root stores water and lets these cacti survive long droughts by shrinking down into the substrate. The flowers are relatively large for such tiny plants — funnel-shaped and borne at the crown in white, cream, pink, magenta or pale yellow, often opening freely over a long season.
Distribution
The genus is endemic to Mexico, concentrated in the arid limestone and gypsum hills of the central and northern states — San Luis Potosí, Nuevo León, Coahuila, Tamaulipas, Querétaro, Zacatecas and neighbouring areas. Plants grow in cracks in rock, on gravelly slopes and in gypsum or clay soils, frequently wedged into crevices where a little extra shelter and run-off collects. Many species have extremely restricted ranges, sometimes a single hillside, which is a large part of why the genus is so vulnerable and so strictly protected.
Notable species
- Turbinicarpus schmiedickeanus — the type species and one of the most variable, encompassing a swarm of named subspecies (such as klinkerianus, macrochele and flaviflorus) with wildly different spination.
- Turbinicarpus pseudomacrochele — noted for long, soft, twisting, curling spines.
- Turbinicarpus lophophoroides — a squat, few-spined species superficially recalling a tiny Lophophora.
- Turbinicarpus alonsoi — a comparatively recent discovery with prominent, elongated tubercles.
- Turbinicarpus valdezianus — a miniature with feathery white spines and disproportionately large violet flowers.
- Turbinicarpus pseudopectinatus — bearing neat, comb-like (pectinate) spines pressed against the body.
Cultivation
Turbinicarpus have a reputation as fussy plants, but the difficulty is almost entirely about the roots and the water. The key is a very lean, sharply draining, mostly mineral mix — plenty of grit, pumice or crushed rock and little organic matter — in a pot deep enough to accommodate the taproot. Give bright light, which keeps the bodies compact and encourages flowering, with only light shade from the harshest summer sun.
Water thoroughly but infrequently in the growing season, always letting the mix dry out completely before the next drink, and keep the plants bone dry and cool through winter. The swollen root rots easily if it sits wet or cold, and root loss is the single most common way these cacti are killed. Growth is slow, so repot infrequently and handle the fragile root with care. See Watering and Repotting for general technique.
Hobby and cultivar notes
Despite their protected status in the wild, Turbinicarpus are surprisingly common and inexpensive in cultivation, because they grow readily from seed and reach flowering size relatively quickly for such slow cacti. Nursery-propagated plants are legal to own and trade domestically in most countries, but because the genus sits on Appendix I, moving them across international borders still requires CITES documentation even for artificially propagated stock; wild-collected material is the real problem, and collecting from habitat is illegal. Growers frequently graft seedlings onto a vigorous rootstock to speed them along and sidestep the touchy taproot, though many prefer the natural look of plants grown on their own roots. Because the genus hybridises freely, seed-grown batches can show pleasing variation, and a number of intergeneric and interspecific crosses circulate among enthusiasts.
Collectors should be aware of the recent move — following molecular studies — to sink Turbinicarpus (along with several allied genera) into Pelecyphora. Both names appear on labels and in the literature; Turbinicarpus remains the name most hobbyists know and use.
See also
- Pelecyphora — the genus into which Turbinicarpus has been merged under the 2022 treatment
- Turbinicarpus schmiedickeanus — the type species
- CITES — the convention regulating trade in these plants
- Grafting · Soil and potting mix · Watering · Repotting · Propagation — seed