Adenia digitata
| Light | Bright light; some direct sun with protection from the harshest midday rays |
|---|---|
| Water | Moderately during active growth; keep dry while dormant and leafless |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Frost-free; keep above about 10 °C in winter |
| Propagation | Seed; stem cuttings also possible (see Propagation — cuttings) |
| Toxicity | Highly toxic — all parts, especially the tuber; harmful to people and pets if eaten |
Adenia digitata is a caudiciform member of the passionflower family (Passifloraceae) from southern and eastern Africa, grown for its swollen water-storing tuber and slender, twining stems bearing deeply divided, hand-shaped leaves. Like many of its relatives in the genus Adenia, it is notably poisonous: the tuber and foliage contain toxic compounds, and the plant is notorious in its native range for poisoning, with recorded cases of fatal accidental, homicidal and suicidal ingestion.
Description
Adenia digitata grows from a large, partly buried caudex — a firm, greyish tuber that stores water and carries the plant through long dry spells. From the top of this tuber rise thin, wiry stems that scramble and twine over surrounding vegetation, often reaching well beyond the modest size of the caudex itself. In cultivation the tuber is frequently raised above the soil to show off its form.
The leaves are the plant's most distinctive feature: they are digitate, divided into several narrow finger-like lobes that spread from a single point, giving a hand- or palm-like outline (the source of the epithet digitata). Foliage is deciduous, appearing with the rains and dropping as the plant enters dormancy. The flowers are small and greenish-yellow, inconspicuous compared with the showy blooms of the related passionflowers, and the species is dioecious, with male and female flowers borne on separate plants. Pollinated female plants produce capsules holding several seeds.
Distribution and habitat
The species is widespread across southern and eastern Africa, growing in bushveld, thornscrub and dry woodland where a buried tuber and a seasonal, drought-avoiding habit are strong advantages. Plants typically root in well-drained soils among rocks, grasses and low shrubs, sending up their annual growth during the warm wet season and retreating to the tuber through the dry months.
Cultivation
Adenia digitata is grown much as other caudiciform succulents are: the priority is a very free-draining, mostly mineral mix and a strong seasonal watering rhythm. Water moderately once the plant is in active leaf, always letting the mix dry between waterings, then taper off and keep it dry as the leaves yellow and drop for its winter rest. Overwatering — especially a wet, dormant tuber in cold conditions — is the quickest way to lose a plant to rot.
Give it bright light, with some direct sun to keep growth compact and the caudex firm; too little light produces thin, over-long stems. Keep it frost-free and warm through winter. Many growers plant it with the tuber partly exposed for display, but young tubers colour and toughen best when grown a little harder. See Watering and Repotting for general technique.
Because every part of the plant is toxic, handle cut stems and tubers with care, wash your hands afterwards, and site the plant well out of reach of children and pets.
Propagation
Seed is the most reliable method and produces well-formed tubers from the start. Sow onto a warm, gritty surface kept lightly moist until germination, then grow the seedlings on cautiously. Stem cuttings can also be rooted, though cutting-grown plants often develop a less shapely caudex and may take time to build a proper tuber. As the species is dioecious, seed set requires both a male and a female plant in flower together.
Common problems
- Tuber rot — almost always from overwatering or a cold, wet dormancy; the caudex softens and discolours. Keep the plant dry while leafless.
- Etiolation — too little light draws the stems out thin and weak and can leave the caudex undersized.
- Pests — mealybugs (white fluff in leaf axils and on stems) and red spider mites in hot, dry air are the usual offenders; see Pests and diseases.
See also
- Adenia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — cuttings · Pests and diseases