Adenium boehmianum
| Light | Full sun to very bright light; the more sun, the sturdier the trunk and the better the flowering |
|---|---|
| Water | Generously while in leaf and growth; keep dry once dormant and leafless in winter |
| Soil | Very free-draining, gritty mineral mix (see Soil and potting mix) |
| Temperature | Warmth-loving; keep well above freezing, ideally above 10 °C; USDA zones 11–12 |
| Propagation | Seed; also cuttings, though these seldom build a good caudex (see Propagation — cuttings) |
| Toxicity | Highly toxic. All parts contain cardiac glycosides; the milky sap is a traditional arrow poison. Keep away from children and pets and wash hands after handling. |
Adenium boehmianum is a stout, deciduous succulent shrub from the arid northwest of southern Africa — chiefly Namibia and southern Angola — and one of the larger-leaved members of the desert rose genus Adenium. It grows a swollen, water-storing trunk topped in the wet season by big, soft, felty leaves and clusters of pink to mauve-purple flowers. Its milky sap is intensely poisonous and was historically used by San (Bushman) hunters to tip arrows, earning it the common name bushman's poison.
Description
Adenium boehmianum forms a thick, grey-barked caudex and a few sparse, club-like branches, reaching perhaps a metre or two in habitat and staying more compact in a pot. Compared with the familiar A. obesum, its leaves are notably large, broad and soft — often velvety with fine hairs — and are carried only during the growing season, dropping as the plant enters dormancy.
The flowers appear in the warm, wet months, typically while the plant is in full leaf. They are trumpet-shaped and a soft pink to violet-mauve, generally without the vivid red throat of many cultivated desert roses, giving the plant a quieter, more pastel look. As with all Adenium, every part exudes a copious white latex when cut.
Distribution and habitat
The species is native to the dry country of northwestern Namibia (including the Kaokoveld) and adjacent southern Angola. It grows on rocky hillsides, among boulders and in coarse, sharply drained soils, enduring long dry seasons by shedding its leaves and living off water stored in the trunk. Rainfall is strongly seasonal, and the plant's whole rhythm — leaf out, flower, then go dormant and leafless — tracks that wet-and-dry cycle.
Cultivation
Grow A. boehmianum much as you would other desert roses: lots of sun, real warmth, and a very free-draining, mostly mineral mix in a pot with ample drainage. During the warm growing season, when the plant is in leaf, water it generously and feed lightly; the large leaves mean it can take more water than a small-leaved succulent while actively growing.
As days shorten and temperatures fall the plant will naturally drop its leaves and go dormant — at that point keep it dry and warm, watering little or not at all until growth resumes. Cold, wet roots are the quickest way to lose one. Because the species dislikes cold, in most climates it is grown as a container plant that can be moved somewhere bright and frost-free for winter. See Watering and Repotting for general technique.
A word of caution: the sap is genuinely dangerous, far more so than most houseplants. Wear gloves or wash thoroughly after pruning, keep cuttings and sap away from eyes and mouth, and site the plant out of reach of children and pets.
Propagation
Seed is the most satisfying method and the one that builds the best swollen trunk. Sow fresh seed onto a warm, gritty, well-aired surface and keep it lightly moist until the seedlings establish; see Propagation — seed. Cuttings will also root, but plants grown from cuttings tend to stay more branch-like and rarely develop the fat caudex that makes the genus so prized — see Propagation — cuttings. Handle all cut material carefully because of the toxic latex.
Common problems
- Rot — the usual killer, caused by watering a dormant or cold plant, or by a mix that holds too much moisture. Roots and caudex soften and discolour.
- Leaf drop out of season — often just a response to cold, underwatering during growth, or a sudden move; the plant is deciduous and losing leaves in autumn is normal.
- Poor flowering / weak growth — nearly always too little light; give it the sunniest spot you have.
- Pests — mealybugs (white fluff in leaf axils and on roots) and spider mites (fine stippling and webbing on the soft leaves) are the ones to watch for. See Pests and diseases.
See also
- Adenium — the desert rose genus overview
- Adenium obesum — the common desert rose, its better-known relative
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases