Adenia spinosa
| Light | Bright light to full sun; give the caudex plenty of light to keep it fat and firm |
|---|---|
| Water | Regularly through the warm growing season once the mix has dried; keep dry while leafless in winter |
| Soil | Very free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Warmth-loving; keep well above freezing, roughly USDA zones 10–11 |
| Propagation | Seed (primary); see Propagation — seed |
| Toxicity | Regarded as toxic — the sap and tissues of Adenia contain harmful compounds; keep away from pets and children |
Adenia spinosa is a robust, caudex-forming succulent from southern Africa and a favourite among collectors of fat-bodied plants. It develops a massive, rounded, greyish caudex that can swell to a considerable size with age, from the top of which sprout scrambling green branches whose tips harden into short spines — the feature that gives the species its name.
Description
Adenia spinosa builds a large, dome-shaped or globose caudex with a smooth, pale grey to greenish skin. In old, well-grown plants this swollen base becomes the dominant feature of the plant, sitting like a boulder above the soil. From the crown it produces thin, scrambling green stems that carry the plant's foliage during the growing season; the ends of these branches stiffen and taper into sharp, spine-like tips.
The leaves are variable and often somewhat lobed, and the plant is deciduous — it drops its foliage and rests as a bare caudex through the dry season. Flowers are small and greenish-yellow, with male and female flowers borne on separate plants (the genus is dioecious), so seed is only set where both sexes grow together.
Distribution and habitat
The species is native to the summer-rainfall regions of southern Africa, where it grows in hot, seasonally dry bushveld and rocky ground. In habitat the bulk of the caudex often sits partly buried, protected from the sun and from browsing animals, with only the branches exposed. Plants endure a long, dry dormant season and grow actively during the warm, wet months.
Like many prized caudex plants, wild populations are vulnerable to over-collection, so nursery- and seed-raised material should always be preferred over plants taken from habitat.
Cultivation
Adenia spinosa is grown for its swollen caudex, and the key to a good specimen is a lean, sharply drained life. Plant it in a very free-draining, mostly mineral mix and give it strong light — full sun in most collections — to keep the body firm and compact rather than soft and etiolated.
Water regularly once the mix has dried during the warm growing season, when the plant is in leaf and actively growing. As the branches yellow and drop in autumn, taper off and keep the plant dry and warm through its leafless winter rest; wet, cold roots in dormancy are the quickest route to rot. Many growers raise the caudex above the soil line over successive repottings to show it off, though in nature it would sit lower. See Watering for general technique.
Propagation
Seed is the usual and most satisfying method, producing plants that build a natural, rounded caudex from the start. Because the species is dioecious, fresh viable seed depends on having both a male and a female plant in flower together. Sow onto a warm, gritty surface and keep lightly moist until germination; see Propagation — seed for a full walkthrough. Cuttings are rarely worthwhile, as they seldom develop the characteristic swollen base.
Common problems
- Rot — the commonest cause of loss, almost always from watering a dormant or cold plant, or from a mix that holds too much moisture around the caudex.
- Etiolation — too little light produces thin, weak stems and a soft body; grow it as bright as you can.
- Pests — mealybugs can lodge in the branch axils and around the crown; spider mites may appear in hot, dry, stagnant conditions. See Pests and diseases.
See also
- Adenia — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases