Cotyledon orbiculata
| Light | Bright light to full sun; the more sun, the whiter the leaf bloom and redder the leaf margins |
|---|---|
| Water | Sparingly; let the mix dry fully between waterings, with a near-dry rest in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Frost-tender; keep above freezing, roughly USDA zones 9b–11 |
| Propagation | Stem and tip cuttings (easy); also seed. Single leaves are unreliable |
| Toxicity | Toxic if eaten; contains bufadienolides (a type of cardiac glycoside) — keep away from pets and especially livestock |
Cotyledon orbiculata is a tough, shrubby succulent from southern Africa, grown for its thick, rounded, chalky-white leaves that are often edged in a fine line of red. Tall flower stalks rise well above the foliage in summer to carry nodding clusters of orange, bell-shaped blooms. Its paddle-like leaves give it the common name pig's ear, and it is also known as round-leafed navel-wort.
Description
Cotyledon orbiculata is an evergreen, much-branched succulent shrublet that typically reaches 30–100 cm tall, forming a rounded bush with age. The opposite leaves are fleshy, obovate to nearly circular, and coated in a powdery white, pruinose bloom (epicuticular wax) that reflects sun and reduces water loss. In bright light the leaf edges develop a thin, decorative red rim. Leaf shape is highly variable across the species' range, and many named forms differ mainly in leaf width, length and margin colour.
In summer the plant sends up long, upright flower stalks, often well above the foliage, each bearing a loose cluster of pendulous, tubular to bell-shaped flowers in orange to orange-red. The nodding flowers are attractive to sunbirds and other pollinators.
Distribution and habitat
The species is widespread across South Africa and neighbouring parts of southern Africa, from the winter-rainfall Western Cape through the Karoo and into summer-rainfall regions. It is a tough, adaptable plant of rocky slopes, ridges and dry scrub, where the waxy leaf coating helps it endure strong sun and long dry spells. Its broad natural range accounts for the many leaf forms seen in cultivation.
Cultivation
Cotyledon orbiculata is one of the easier succulents to grow and a good choice for beginners. Give it a very free-draining, mostly mineral mix and as much light as you can — full sun outdoors in mild climates produces the whitest leaves, the reddest margins and a compact, sturdy habit. In too much shade the plant stretches and the leaf colour fades.
Water thoroughly once the mix has dried out, then let it dry again; the fleshy leaves store plenty of moisture, so err on the side of underwatering. Reduce water sharply in winter to prevent rot. The plant is frost-tender and should be kept above freezing — grow it in a container to bring under cover where winters are cold. See Watering and Repotting for general technique. The powdery bloom on the leaves is easily rubbed off by handling and does not regrow on that leaf, so move plants by the pot rather than the foliage.
Propagation
Propagation is easy from stem cuttings and from seed. Stem or tip cuttings root readily: take a healthy shoot, let the cut end callus for a few days, then insert it into a gritty mix and water lightly once roots begin. Unlike many leaf-propagating succulents, Cotyledon does not reliably grow from a single detached leaf, so use stem cuttings or sow seed on a fine mineral surface. See Propagation — cuttings and Propagation — seed for full walkthroughs.
Cultivars
Several forms and cultivars are grown for foliage. The variety oblonga (sometimes sold as undulata) has narrower, wavy-edged, intensely white leaves and is a favourite for its wavy "silver crown" look. Compact, broad-leaved and heavily powdered selections are also common in the trade, usually chosen for leaf shape and the vividness of the red margin.
Common problems
- Rot — the most common cause of loss, almost always from overwatering or a slow-draining mix; leaves and stems soften and blacken.
- Etiolation — too little light makes the plant stretch, with widely spaced, dull, pale leaves that flop.
- Lost bloom — the attractive white bloom rubs off permanently where leaves are touched; handle by the pot.
- Pests — mealybugs (white fluff in leaf axils) and occasionally aphids on the flower stalks are the usual culprits; see Pests and diseases.
See also
- Cotyledon — the genus overview
- Propagation — cuttings · Soil and potting mix · Watering · Repotting