Sulcorebutia albissima
| Light | Bright light; a few hours of direct sun with protection from the harshest afternoon glare |
|---|---|
| Water | Moderate in the growing season, letting the mix dry between waterings; keep dry and cool in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; happiest in USDA zones 9–11 |
| Propagation | Seed and offsets; sometimes grafted to speed growth |
| Toxicity | Non-toxic to cats and dogs |
Sulcorebutia albissima is a small, clustering globular cactus from the Bolivian highlands, prized among collectors for the dense, pale pectinate spines that lie flat against the body and cloak it almost completely. The comb-like spination sets off the vivid purple-pink flowers that ring the plant in spring, a contrast that makes it one of the most sought-after species in the genus. It belongs to the genus Sulcorebutia, a group of dwarf South American cacti much loved for their brilliant blooms.
Description
Sulcorebutia albissima forms a small, flattened-globular body, usually only a few centimetres across, that offsets with age to build up low clumps. The stem is divided into many small tubercles arranged in neat spirals, each bearing an elongated areole. From these areoles grow short, fine spines held tight against the body in a comb-like (pectinate) arrangement — their chalky white to pale greyish colour, dense enough to largely obscure the green skin beneath, is the trait that gives the species both its name (albissima meaning "whitest") and its appeal.
Flowers appear in spring, opening in a ring around the sides of the plant. They are a rich purple to magenta-pink, funnel-shaped and glossy, and their saturated colour stands out dramatically against the pale spination. Like most of the genus, the plant has a comparatively large taproot relative to its modest top growth.
Distribution and habitat
The species is native to the mountains of Bolivia, where members of the genus grow at high elevation in rocky, well-drained ground among grasses and low scrub. In habitat these plants endure bright sun, wide swings between day and night temperatures, and a pronounced dry season, retreating into their roots and the surrounding grit during the coldest, driest months. As with all cacti, wild collection is discouraged and the family is listed under CITES; nursery-grown plants are widely available and are the responsible choice.
Cultivation
Sulcorebutia albissima is a rewarding plant for a collector who can resist overwatering. Grow it in a gritty, mostly mineral mix in a pot deep enough to accommodate the taproot, and give it bright light with a few hours of sun — good light keeps the spination dense and pale and encourages flowering, while too little draws the body out and dulls the plant. Water moderately through the warm months once the mix has dried, then keep it dry and cool over winter. A cold, dry winter rest is important: it hardens the plant, helps prevent rot, and is the key to a generous spring flowering. See Watering and Repotting for general technique.
Grown hard and cool, the species is fairly forgiving; the main risk is a wet, stagnant root run, especially in cold weather.
Propagation
The species can be raised from seed, which germinates readily on a warm, gritty surface kept lightly humid, and this is how most named collections are increased. Established plants also cluster, so mature clumps can be divided and the offsets rooted once any cut surfaces have callused. Slow or difficult seedlings are sometimes grafted onto a vigorous rootstock to speed them along, then grown on their own roots later.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a slow-draining mix, or wet conditions in winter; the plant softens from the base.
- Etiolation — too little light makes the body elongate and the spines thin out, spoiling the tight, pale-clothed look.
- Pests — mealybugs (including root mealybugs on the taproot) and red spider mites are the most common; check the areoles and roots at repotting time. See Pests and diseases.
See also
- Sulcorebutia — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Propagation — offsets