Trichodiadema densum
| Light | Bright light to full sun; several hours of direct sun keep it compact and flowering |
|---|---|
| Water | Moderate during active growth, drying out between waterings; much less during its dormant rest |
| Soil | Gritty, very free-draining mix (see Soil and potting mix) |
| Temperature | Fairly hardy for a mesemb — takes light frost (to about −4 °C / 25 °F) when kept dry, but safest frost-free; roughly USDA zones 9b–11 |
| Propagation | Cuttings and division (easy); also seed |
| Toxicity | Not known to be toxic to cats or dogs |
Trichodiadema densum is a small, clump-forming succulent from South Africa that builds up low cushions of short, plump green leaves, each tipped with a neat crown of fine white bristles that make the plant look uncannily like a tiny cactus. In late winter and spring it is smothered in vivid magenta, daisy-like flowers, and with age it develops a swollen, gnarled, tuberous rootstock that makes it a popular subject for bonsai-style succulent pots. It belongs to the ice-plant family, Aizoaceae, and to the genus Trichodiadema.
Description
Trichodiadema densum is a dwarf, mat-forming succulent that rarely rises more than a few centimetres above the soil, spreading instead into dense green cushions. The small, cylindrical, finger-like leaves are fleshy and bright green, set closely in rows, and each is topped by a rosette of short, radiating white bristles — the "crown" of the genus (Greek diadema, a diadem) that gives it its name. These bristle-tufts are the plant's most distinctive feature and are the reason it is so often mistaken for a miniature cactus, though it is not related to the cactus family at all.
Below ground, older plants thicken into a fat, tuberous, caudex-like taproot. Growers often lift the plant a little at each repot to expose this gnarled root, producing the characteristic "old bonsai" look prized in cultivation.
The flowers are the real show: bright magenta to purple-pink, many-petalled and daisy-like, borne in profusion from autumn to spring with a peak in late winter, and opening in bright sunshine. They sit close over the foliage and can hide the leaves entirely at peak bloom.
Distribution and habitat
The species is native to the Western and Eastern Cape of South Africa — the Little Karoo and the Willowmore district — where it grows in dry, open scrub and rocky, gritty ground, often in rock crevices. Like many small mesembs it endures long dry spells and strong sun in habitat, taking most of its water in the cooler part of the year and sitting out the hot, dry summer in a semi-dormant state. Its low, cushiony habit and swollen root are adaptations to this lean, exposed environment.
Cultivation
Trichodiadema densum is one of the easier "living-stone relatives" to grow and is forgiving enough for a keen beginner. Give it a gritty, sharply draining mix and the brightest position you can offer — plenty of direct sun keeps the cushions tight and the bristle-crowns well formed, while too little light makes the plant stretch and sprawl.
Water moderately through the active growing period, letting the mix dry out between waterings, and ease right off when it rests so the roots stay firm. As with most leaf succulents, overwatering in cool, dark conditions is the main cause of loss. It tolerates a touch of frost when dry, but is safest kept frost-free and on the dry side through winter. For the classic caudex display, pot it a little deep at first and raise the swollen root gradually over successive repottings. See Watering and Repotting for general technique.
Propagation
This is an obliging plant to increase. Stem cuttings root readily: take a short piece, let the cut surface callus for a day or two, then set it in gritty, barely moist mix. Established clumps can also be lifted and divided. Seed is straightforward too and is the usual route if you want many plants or a fresh batch of thick young rootstocks to train. See the linked guides for full walkthroughs.
Common problems
- Rot — from overwatering or a slow-draining mix, especially in winter; leaves and stems go soft and translucent.
- Etiolation — in too little light the cushions loosen, stems stretch, and the tidy bristle-crowns become sparse.
- Pests — mealybugs (white fluff in leaf axils and around the roots) and the occasional aphid on flower buds are the usual visitors. See Pests and diseases.
See also
- Trichodiadema — the genus overview
- Aizoaceae — the ice-plant / mesemb family
- Soil and potting mix · Watering · Repotting · Propagation — cuttings · Propagation — seed