Caralluma socotrana
| Light | Bright light with some shade from harsh afternoon sun; good airflow |
|---|---|
| Water | Sparingly in the growing season; keep dry and rested in winter |
| Soil | Very free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Warmth-loving and notably cold-sensitive; keep frost-free and ideally above roughly 12 °C in winter |
| Propagation | Stem cuttings (primary); seed |
| Toxicity | No established food use; keep out of reach of curious pets |
Caralluma socotrana is a clump-forming stapeliad first described from the island of Socotra, in the Caralluma genus of the dogbane family (Apocynaceae, milkweed subfamily). It is now more usually placed in the genus Monolluma, as Monolluma socotrana, the older Caralluma combination being treated as a synonym. It forms clusters of stout, upright, knobbly grey-green stems edged with soft tubercles, and bears clusters of small, dark, star-shaped flowers with the faint carrion scent typical of the group — a lure for the flies that pollinate them.
Description
Caralluma socotrana is a leafless stem succulent that grows in low clumps of erect to spreading shoots, giving the plant a coral-like look. The stems are rather thick and bluntly angled, with a matte grey-green to bluish surface and soft, tooth-like tubercles running along the angles. As with other stapeliads, the "leaves" are reduced to small, quickly-shed points on these teeth, so the green stems do the work of photosynthesis and water storage.
The flowers appear in small clusters, usually toward the upper part of the stems. They are modest in size and dark in colour — variously described from dull red through maroon to near-blackish purple — and open into the five-pointed star shape characteristic of the carrion-flower group. A slight unpleasant scent and the dark corolla work together to attract small flies, which pollinate the blooms.
Distribution and habitat
The species occurs on the Socotra archipelago in the Arabian Sea (part of Yemen) and, contrary to what its name suggests, extends across the adjacent Horn of Africa, being recorded from Ethiopia, Somalia and Kenya; it is not a Socotran endemic. Throughout this range it grows among rocks and in open, well-drained ground in arid country. In habitat the plants endure long dry spells, strong light and sharp drainage, often tucked among stones or low vegetation that gives a little shade at the roots.
As with any wild succulent, plants in cultivation should come from nursery-propagated stock rather than habitat collection.
Cultivation
Caralluma socotrana has a reputation as one of the more demanding stapeliads, and is happiest kept warm, bright and above all dry at the roots when not in active growth. Grow it in a very free-draining, largely mineral mix in a shallow, well-aerated pot. Give bright light — which keeps the stems compact and well-coloured — with a little shade from the fiercest afternoon sun to prevent scorching.
Water thoroughly during the warm growing season once the mix has dried, then ease off sharply as temperatures fall; through the cool months keep the plant nearly dry. Cold, damp conditions are the enemy, and this species resents chilling more than most, so aim to keep it frost-free and comfortably warm in winter. Good airflow around the stems helps prevent rot and fungal marking. See Watering and Repotting for general technique.
Propagation
The easiest method is by stem cuttings. Detach a healthy segment, let the cut surface dry and callus for a few days, then set it on a barely-moist mineral mix in warmth until roots form. Established clumps can also be divided at repotting. Seed is possible where fresh material is available, sown on a warm, gritty surface, though germination and early growth ask for more patience. See Propagation — cuttings and Propagation — seed.
Common problems
- Rot — the usual cause of loss; almost always from overwatering, a slow-draining mix, or cold damp conditions. Stems soften and blacken, often from the base.
- Etiolation — too little light makes the stems thin, pale and stretched, losing their sturdy, knobbly form.
- Pests — mealybugs (white fluff in the stem grooves and at the roots) and, in dry stagnant air, spider mites are the most common; stem rot can follow damage or bruising.
See also
- Caralluma — the genus overview
- Soil and potting mix · Watering · Propagation — cuttings · Propagation — seed · Repotting · Pests and diseases