Copiapoa cinerea var. columna-alba
| Light | Very bright light to full sun; acclimatise gradually to avoid scorch |
|---|---|
| Water | Very sparingly; drought-tolerant, with a completely dry winter rest |
| Soil | Gritty, low-organic mineral mix (see Soil and potting mix) |
| Temperature | Keep frost-free and dry in winter, ideally above ~10 °C (50 °F); roughly USDA zones 10–11 |
| Propagation | Seed (primary); offsets from the occasional clustering plant |
| Toxicity | Non-toxic to cats and dogs |
Copiapoa cinerea var. columna-alba is a strikingly white-bodied, columnar cactus from the coastal Atacama Desert of northern Chile. A geographically distinct variety of the chalky-skinned Copiapoa cinerea, it forms tall, upright columns — usually solitary, occasionally offsetting with age — clad in a pale, ashy epidermis and armed with only sparse, short spines. It is one of the most sought-after of the copiapoas for its ghostly-white stems and slow, sculptural growth.
Description
Copiapoa cinerea var. columna-alba grows as an erect cylindrical column, typically taller and more slender than the broadly globular typical form of C. cinerea, reaching roughly 50–75 cm tall and 10–20 cm across. Plants are usually solitary, though old specimens may occasionally offset from the base to form a small cluster of parallel columns. The stem carries numerous low ribs bearing felted areoles set along the ridges.
The most distinctive feature is the body colour: a chalky, greyish-white to pale bluish coating over green tissue. This waxy, powdery bloom reflects the fierce coastal sun and is thought to help the plant cope with intense light and heat. Spines are few and short — usually one to three dark, stiff central spines per areole, with young plants often almost spineless and the thin radial spines mostly lost in maturity, leaving much of the pale surface exposed. Flowers appear from the woolly crown, opening a clear yellow, and are followed by small fruits.
Distribution and habitat
The variety is native to a narrow strip of the Atacama Desert along the Chilean coast, one of the driest environments on Earth. Here almost no measurable rain falls for years at a stretch; the plants instead depend on the camanchaca, the dense coastal fog that rolls in off the Pacific and condenses on their surfaces. They grow on arid slopes and gravelly flats fully exposed to sun and salt-laden wind, often in loose colonies where they are among the few plants able to survive.
Like all Copiapoa, the variety is slow-growing and long-lived, and wild populations are vulnerable to illegal collection and habitat disturbance. The genus is listed under CITES Appendix II; nursery-grown, seed-raised plants are the responsible way to grow it, and collecting from habitat is not.
Cultivation
This is a plant that rewards patience and punishes overwatering. Grow it in a very free-draining, mostly mineral mix in a deep pot to accommodate its roots, and give it the brightest position you can — near-full sun suits it, though plants raised under glass should be acclimatised slowly so the pale skin is not scorched.
Water only occasionally during the warm growing months, letting the soil dry out completely each time, and keep the plant bone-dry and frost-free through winter — a warm, dry rest around 10 °C suits it. Good air movement helps preserve the chalky bloom on the epidermis, which is easily marked by splashing or handling. Growth is genuinely slow, so expect to measure progress over years rather than seasons. See Watering and Repotting for general technique.
Propagation
Seed is the usual and most reliable method; the fine seed germinates on a warm, gritty surface kept lightly humid, after which seedlings are grown on very cautiously as they are prone to rot when young. See Propagation — seed. The occasional plant that offsets can also be increased by removing and rooting offsets once they have formed their own basal roots — allow any cut surface to callus well before potting up. See Propagation — offsets.
Common problems
- Rot — by far the commonest cause of loss, almost always from too much water or a mix that holds moisture; the base or core softens and discolours.
- Loss of the white bloom — the powdery coating can be rubbed off by handling or spotted by hard water, leaving permanent marks; try to keep water off the body.
- Etiolation — too little light makes the column grow thin, greener and drawn-out, losing its compact, chalky character.
- Pests — mealybugs (white fluff in the areoles and at the roots) and red spider mites are the usual offenders under glass.
See also
- Copiapoa — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets