Edithcolea grandis
| Light | Bright light; warmth-loving, tolerates some direct sun with acclimatisation |
|---|---|
| Water | Very sparingly; let the mix dry fully, keep nearly dry and warm through winter |
| Soil | Extremely free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Warmth-loving; keep well above freezing, ideally no cooler than about 10 °C; USDA zones 10–11 |
| Propagation | Stem cuttings (dried and rooted warm); seed; frequently grafted for security |
| Toxicity | Not considered toxic to cats and dogs; flowers smell of carrion to attract fly pollinators |
Edithcolea grandis is a sprawling, spineless stem succulent of the milkweed family (Apocynaceae), famous for its enormous, intricately patterned star-shaped flowers. Marbled and freckled in deep red and yellow and fringed with fine hairs, the blooms have earned it the common name Persian carpet flower. It is the only widely grown member of its genus, Edithcolea, and has a reputation among growers as beautiful but demanding.
Description
Edithcolea grandis forms low clumps of angular, greyish-green stems that sprawl and lean rather than stand upright. The stems are four- to five-angled and lined with soft, toothed tubercles along each edge, giving them a spiky silhouette without true spines. Colour varies with light and stress, from dull green in shade to a purplish or bronzed cast in strong sun.
The flowers are the plant's glory: large, flat, five-pointed stars intricately banded and speckled in maroon, brick-red and yellow, with a delicately hair-fringed margin. Like other carrion-flower stapeliads, including its Stapelia relatives, the blooms give off a faint fetid scent to attract the flies that pollinate them. Fertilised flowers may be followed by the paired, horn-like seed pods typical of the family.
Distribution and habitat
The species is native to arid parts of northeast and East Africa and the southern Arabian Peninsula, with a well-known population on the island of Socotra. It grows in hot, dry, rocky terrain, typically tucked among stones or under the light shade of low shrubs, where its sprawling stems can shelter from the fiercest midday sun. These origins explain its dislike of cold and damp in cultivation: it is adapted to warmth, sharp drainage and long dry spells.
Cultivation
Edithcolea grandis has a well-earned reputation as a challenging plant, and rot is by far the most common cause of loss. Success comes from mimicking its habitat: an extremely free-draining, mostly mineral mix, a warm position, and very cautious watering. Water only when the mix has dried completely and the plant is in active growth, and keep it nearly dry and warm through the cooler months rather than exposing it to a cold, wet winter rest.
Warmth is key — this species resents chilly nights far more than most succulents, and cold combined with moisture is usually fatal. Give it bright light to keep the stems compact and well-coloured, with only a little shade from the most intense afternoon sun. Because plants on their own roots can be short-lived, many growers keep a backup by grafting a stem onto a hardier, more rot-resistant stapeliad rootstock, which can improve vigour and survival. See Repotting for general technique, and handle the brittle stems gently.
Propagation
The usual method is stem cuttings. Detach a healthy stem, let the cut end dry and callus for several days, then set it on a warm, gritty rooting mix kept barely moist until roots form. Cuttings can be slow and are prone to rotting if kept too wet, so err on the dry side and provide plenty of warmth. Seed is also possible where fresh, viable seed can be obtained (see Propagation — seed), and grafting onto a robust rootstock is a reliable way to establish and grow on difficult material.
Common problems
- Rot — the number-one killer, brought on by cold, overwatering, or a mix that holds moisture; stems soften, discolour and collapse, often from the base.
- Cold damage — even brief exposure to low temperatures, especially while damp, can cause blackening and dieback.
- Pests — mealybugs (white fluff in the crevices and on roots) and the occasional infestation of spider mites; inspect regularly, as pests exploit stressed plants. See Pests and diseases.
See also
- Edithcolea — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Pests and diseases