Cyphostemma currorii
| Light | Full sun; bright light year-round |
|---|---|
| Water | Generously in summer growth; keep completely dry through winter dormancy |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep well above freezing; frost-tender, roughly USDA zones 10–11 |
| Propagation | Seed (primary); large cuttings possible but slower |
| Toxicity | Sap and fruit contain irritant calcium oxalate crystals; treat as toxic to pets and people |
Cyphostemma currorii is a large, tree-forming succulent from the arid uplands of Namibia and southwestern Angola, and one of the most imposing members of the genus Cyphostemma. It builds a massive, water-storing (pachycaul) trunk topped by a few stout, fleshy branches, and is wrapped in distinctive papery, peeling bark that flakes away in yellowish, cream and coppery sheets — a look that has earned it common names such as cobas (kobas) and butter tree. Despite its bloated, desert-tree appearance it belongs to Vitaceae, the same family as the cultivated grape.
Description
Cyphostemma currorii is a stem succulent that in habitat grows into a squat tree several metres tall, with a swollen, tapering trunk that can become very thick and stores water against long droughts. The trunk and main limbs are clothed in smooth, papery bark that continually peels in thin, translucent layers, exposing greenish, pale or bronzed skin beneath.
The plant is deciduous, carrying leaves only during the warm growing season. The foliage is large, fleshy and somewhat grape-like — divided into leaflets with irregularly toothed margins and bright green. Small, inconspicuous greenish-yellow flowers are borne in branched clusters and are followed by tight bunches of grape-like berries that ripen red. As in true grapes the fruit and sap are laden with needle-like calcium oxalate crystals (raphides), so the berries are not edible and the juice can irritate skin.
Distribution and habitat
The species is native to the dry country of central and northern Namibia and adjacent southwestern Angola, where it grows on rocky hillsides, granite outcrops and among boulders in open, sun-baked terrain. It is adapted to a climate of intense sun, high heat and a short, unreliable rainy season followed by a long dry winter, which it passes leafless and dormant. Its swollen trunk and deep-rooting habit let it anchor into rock crevices and ride out extended drought.
Cultivation
Cyphostemma currorii is a slow, characterful subject prized by caudex and succulent collectors, and it is grown much like its relatives in the genus. The single most important thing is a very open, gritty, mostly mineral mix in a container with generous drainage, as the fat trunk rots quickly if kept wet and cold.
Give it as much direct sun as you can — full sun produces a compact plant with a well-formed trunk, while too little light causes weak, drawn growth. Water freely while it is in active leaf during the warm months, letting the mix dry between soakings, then reduce watering as the leaves yellow and drop and keep it completely dry and frost-free through its winter dormancy. It resents cold, wet conditions above all. See Watering and Repotting for general technique; the peeling bark is normal and should never be picked at.
Propagation
Seed is the usual and most reliable method. Fresh seed sown onto a warm, gritty surface and kept lightly moist germinates fairly readily, and seed-grown plants tend to develop the best-proportioned caudex over time. Large stem cuttings can sometimes be rooted, but they are slower to establish a good trunk and are far less commonly used. See Propagation — seed and Propagation — cuttings for full walkthroughs.
Common problems
- Rot — the commonest killer, almost always from overwatering, poor drainage, or water combined with winter cold; the trunk softens and discolours.
- Etiolation — insufficient light produces thin, elongated, weak growth and a poorly formed trunk.
- Skin irritation — the sap and crushed fruit contain irritant oxalate crystals, so wear gloves when pruning or repotting and keep the fruit away from children and pets.
- Pests — mealybugs (white fluff in leaf axils and on roots) and spider mites in hot, dry, still air are the usual offenders. See Pests and diseases.
See also
- Cyphostemma — the genus overview
- Cyphostemma juttae — a smaller, widely grown relative
- Grafting · Soil and potting mix · Watering · Repotting · Propagation — seed