Monadenium guentheri
| Light | Bright light to light shade; more sun brings out compact growth and darker markings |
|---|---|
| Water | Regularly in the warm growing season once the soil dries; keep dry and dormant in winter |
| Soil | Fast-draining gritty mix (see Soil and potting mix) |
| Temperature | Keep above about 10 °C; frost tender, USDA zones 10–11 |
| Propagation | Stem cuttings (easy), division of clumps, or seed |
| Toxicity | Caustic milky latex; irritant to skin, eyes and mucous membranes — handle with care |
Monadenium guentheri is an easy, fast-clumping succulent from East Africa, grown for its curiously bumpy cylindrical stems that rise from a swollen tuberous root. The stems are lined with spiralling tubercles (low, tooth-like bumps), each tipped with a tiny fleeting leaf, giving the plant a knobbly, reptilian texture that collectors find irresistible. It is one of the most forgiving members of the genus Monadenium and a good introduction to these unusual relatives of the spurges.
The genus Monadenium is nowadays folded by many botanists into the huge genus Euphorbia, and this plant is accordingly also seen under the name Euphorbia guentheri. Whichever label the pot carries, its care and habit are the same.
Description
Monadenium guentheri produces upright to sprawling cylindrical stems, typically finger-thick (about 2 cm across); they may lengthen to as much as 90 cm but are often shorter, creeping or pendent, and the plant offsets freely to form a low, congested clump. Each stem is patterned with rows of rounded tubercles arranged in gentle spirals, and from the tip of each tubercle a small, spoon-shaped leaf appears during active growth, only to drop as conditions dry. The overall effect is a green, warty column rather than a smooth or heavily spined body.
Below ground the plant develops a thickened, tuberous rootstock that stores water and helps it survive seasonal drought. As in all members of the group, the small flowers are enclosed in a specialised cup-like structure (the cyathium) rather than being showy true flowers; in Monadenium this cup is characteristically one-sided and often greenish to pinkish, appearing among the upper tubercles.
Like all spurges, the plant is filled with a white latex that flows freely when any part is cut or bruised.
Distribution and habitat
Monadenium guentheri is native to Kenya, in tropical East Africa, where it grows in open grassy scrub and dry bushland at moderate elevations. In habitat it experiences a warm wet season followed by a long dry rest, and the tuberous root is an adaptation to exactly this rhythm. Plants often grow among grass and low scrub that give them a little shade and shelter.
Cultivation
This is one of the easier caudiciform-rooted succulents to keep, and it grows quickly for a plant of its kind. Give it a very free-draining, gritty mix and a pot that accommodates the spreading clump. Through the warm months water thoroughly whenever the soil has dried, and the plant will grow with enthusiasm; as light and temperatures fall in autumn, taper off and keep it dry and warm over winter, when it naturally rests and may drop most of its leaves.
Position it in bright light. It tolerates light shade, but stronger light keeps the stems short, fat and well-marked instead of thin and stretched. Protect it from frost — it is strictly a warm-climate or indoor/greenhouse plant in cold regions. See Watering and Repotting for general technique.
A word of caution when handling: the milky latex is caustic and can irritate skin and eyes badly, so wear gloves when taking cuttings or repotting and keep it away from your face. Keep the plant out of reach of children and pets.
Propagation
Propagation could hardly be simpler. Stem cuttings root readily: sever a stem, rinse or blot away the bleeding latex, let the cut end callus for several days in a dry, shaded spot, then set it in barely-moist gritty mix until roots form. Established clumps can also be lifted and divided, and the species sets seed that germinates well on a warm, mineral surface. See Propagation — cuttings, Propagation — offsets and Propagation — seed for full walkthroughs.
Common problems
- Rot — the usual cause of loss, brought on by wet, cold, or poorly-drained conditions, especially in winter; the tuberous root and stem bases soften and blacken.
- Etiolation — too little light draws the stems out thin and pale, blurring the tidy tuberculate pattern.
- Pests — mealybugs (white fluff between the tubercles and at the roots) and the occasional spider mite are the main nuisances. See Pests and diseases.
See also
- Monadenium — the genus overview
- Euphorbia — the larger genus into which Monadenium is now often merged
- Propagation — cuttings · Propagation — offsets · Soil and potting mix · Watering · Repotting