Eriosyce islayensis
| Light | Very bright light to full sun |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, dry winter rest |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; tolerates cool, mild coastal conditions |
| Propagation | Seed |
| Toxicity | Non-toxic to cats and dogs |
Eriosyce islayensis is a small, solitary, globe- to barrel-shaped cactus from the fog-swept coastal deserts of southern Peru, and the type species of the former genus Islaya. It has a firm grey-green to blue-green body armoured with stiff spines, and produces small yellow flowers from a woolly crown, followed by conspicuous bright red, club-shaped fruits. Once split among many narrow species of Islaya, these coastal plants are now generally treated within the broad genus Eriosyce.
Description
Eriosyce islayensis is usually a solitary plant, forming a flattened globe to short cylinder up to roughly 10–20 cm tall and about as wide, though older specimens can become larger and more columnar. The body is grey-green, blue-green or almost brownish, its low ribs broken into tubercles, each bearing an areole set with felt and stiff, straight to slightly curved spines. Radial and central spines vary a good deal between populations, from short and pale to longer and dark, which is one reason so many of these coastal plants were once described as separate species.
Flowers appear at the woolly apex, small and funnel-shaped, in shades of pale to bright yellow, often flushed reddish outside. They are followed by the plant's most distinctive feature: elongated, club-shaped fruits that ripen a vivid red and are hollow at maturity, standing out against the dull body and helping to distribute the small black seeds.
Distribution and habitat
The species grows along the arid Pacific coast of southern Peru, in one of the driest regions on Earth. Rainfall there is negligible for years at a time, and the plants depend heavily on the camanchaca — the dense marine fog that rolls inland off the cold Humboldt Current. Moisture condensing from this fog on the spines and body is a key part of how these cacti survive.
Plants typically grow on gravelly slopes, coastal terraces and sandy flats near the sea, often in company with other fog-desert specialists. In drought the body contracts and takes on a dull, dusty cast, then plumps up and greens after fog or the rare shower.
Cultivation
Eriosyce islayensis is a slow, tough plant that rewards restraint. Grow it in a very free-draining, mostly mineral mix and give it as much light as you can — near full sun suits it and keeps the body compact and well-spined. Water thoroughly only when the soil has dried out completely, and cut back sharply in winter, keeping the plant cool and dry to prevent rot. It appreciates good airflow and, coming from a cool coastal climate, dislikes prolonged hot, stuffy conditions.
Like many slow desert cacti, it is far more often lost to overwatering than to neglect. See Watering and Repotting for general technique, and give it a snug pot rather than an oversized one.
Propagation
Seed is the standard and usually the only method, as the plant rarely offsets. Sow the fine seed on a warm, mineral surface kept humid until germination, then grow the seedlings on carefully — they are small and slow at first. Some growers graft young seedlings to speed early growth before returning them to their own roots. See Propagation — seed for a full walkthrough.
Common problems
- Rot — almost always from overwatering, a slow-draining mix, or water sitting in the crown; the body softens and discolours from the base or apex.
- Etiolation — too little light makes the body pale, soft and elongated, with weaker spination.
- Pests — mealybugs (white fluff in the areoles, and on the roots) and red spider mites (fine webbing, bronzed skin) are the usual offenders. See Pests and diseases.
See also
- Eriosyce — the genus overview (including the former Islaya)
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting