Monadenium ritchiei
| Light | Bright light with some shade from harsh midday sun; a little morning sun brings out stem colour |
|---|---|
| Water | Moderately in growth, letting the mix dry between waterings; keep dry through the winter rest |
| Soil | Fast-draining, gritty mineral mix (see Soil and potting mix) |
| Temperature | Warmth-loving; keep above about 10 °C and protect from frost (roughly USDA zones 10–11) |
| Propagation | Stem cuttings (primary); also from seed |
| Toxicity | Milky sap is a skin and eye irritant and toxic if ingested; handle with care and keep away from pets |
Monadenium ritchiei is a small, clump-forming succulent from Kenya, grown for its plump, richly tuberculate green stems and its charming pink cup-shaped floral bracts. Now classified by many botanists within Euphorbia (as Euphorbia ritchiei), it belongs to the genus Monadenium, a group of African succulent spurges closely allied to the true euphorbias. It is an easy, characterful plant that has become especially popular in a striking variegated form.
Description
Monadenium ritchiei forms low clusters of thick, upright to sprawling stems and spreads by underground shoots, building up into broad clumps over time. The stems are cylindrical and covered in prominent rounded tubercles arranged in spiralling rows, giving the surface a knobbly, almost beaded texture. Small, short-lived leaves appear near the growing tips in the active season and are shed as conditions dry, leaving the sculptural stems as the main feature for most of the year.
Like other members of the genus, its flowers are tiny and are surrounded by showy, cup-shaped bracts — in this species a clear pink — that appear near the stem tips and are far more conspicuous than the true flowers within. As in all euphorbias, cut or broken tissue exudes a milky white latex that is irritating to skin and eyes.
Distribution and habitat
The species is native to Kenya, where it grows on hot, stony slopes and among rocks with sharp drainage, at around 1,300 m elevation in the Meru region south-west of Isiolo. In habitat it experiences a warm growing season with seasonal rains followed by a long dry rest, a rhythm worth keeping in mind in cultivation.
Cultivation
Monadenium ritchiei is one of the more forgiving succulent spurges and makes a rewarding pot plant. Grow it in a very free-draining, mostly mineral mix in a pot that is not too large, in bright light with a little shade from the fiercest midday sun. Water moderately while the plant is in active growth, always letting the mix dry out before watering again, and keep it dry and warm through winter when growth stops. Cold, wet conditions are the main danger and readily cause rot.
Take care when handling or pruning: the milky sap can irritate skin and is especially harmful to the eyes, so wash off any contact and keep it away from children and pets. See Watering and Repotting for general technique.
Propagation
The easiest method is by stem cuttings. Sever a stem cleanly, rinse or blot away the milky sap, and allow the cut to callus for several days in a dry, shaded spot before setting it in a gritty, barely moist mix to root. Warmth speeds the process. The species can also be raised from seed where it is available. See Propagation — cuttings for a full walkthrough.
Cultivars
A variegated form is widely grown and highly sought after, its stems marbled and splashed with cream, yellow or pink against the green. Because variegated tissue carries less chlorophyll, these plants grow more slowly and appreciate bright but not scorching light to keep their colours strong without burning. They are usually increased from cuttings of well-marked stems.
Common problems
- Rot — almost always from overwatering, a poorly draining mix, or cold wet winters; stems soften and discolour, often from the base.
- Etiolation — too little light causes weak, stretched stems with widely spaced, flattened tubercles.
- Pests — mealybugs (white fluff between the tubercles and at the roots) and spider mites are the usual culprits; see Pests and diseases.
- Sap irritation — not a plant problem but a grower one: the latex stings skin and eyes, so always handle cut stems with care.
See also
- Monadenium — the genus overview
- Euphorbia — the closely allied genus in which this species is often placed
- Propagation — cuttings · Soil and potting mix · Watering · Pests and diseases