Edithcolea

Edithcolea is a small genus of clump-forming stem succulents in the milkweed family (Apocynaceae, subfamily Asclepiadoideae), native to the drylands of northeastern Africa and the southern Arabian Peninsula. Placed among the stapeliads — the so-called carrion-flower group — it is grown almost entirely for one thing: its extraordinary star-shaped flowers, boldly patterned in maroon, cream and gold and fringed with fine hairs, which have earned the plant the common name Persian carpet flower. In cultivation the genus is treated as effectively monotypic, centred on the widespread and variable Edithcolea grandis. It has a well-deserved reputation as one of the more challenging succulents to keep alive, especially on its own roots.

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Description

Edithcolea plants form low, spreading clumps of fleshy, four- to five-angled stems that are typically grey-green and often mottled or tinted with purple in strong sun. The stem margins are lined with firm, spreading teeth, each tipped with a small spine, giving the stems a distinctly toothed, sculptural outline. The stems remain relatively short and tend to sprawl or lean rather than stand upright, rooting where they touch the ground to build a slowly widening mat.

The flowers are the whole point of the plant. Borne singly or a few at a time near the stem tips, they are broadly star-shaped and can be strikingly large for the size of the plant, with five pointed lobes. The surface is patterned in a dense mosaic of maroon to purple-brown markings over a cream to yellow ground, and the lobe margins carry a fringe of fine, purple, club-tipped hairs that tremble in the slightest air movement. Like other stapeliads, the flowers are pollinated by flies, drawn by a carrion scent.

Distribution

The genus occurs across a broad but discontinuous range in northeastern Africa — including Somalia, Ethiopia, Kenya and adjacent countries — and extends across the Red Sea into the southern Arabian Peninsula. Plants grow in hot, arid to semi-arid habitats, typically tucked among rocks, in the light shade of shrubs, or in gritty, sharply drained soils where they are sheltered from the most intense sun and never sit in moisture for long.

Cultivation

Edithcolea has a reputation as a "grower's graveyard," and the difficulty is real: the plants are exceptionally intolerant of cold and of excess moisture, and rot can move through a clump alarmingly fast. Success comes from mimicking the hot, sharply drained conditions of habitat.

Warmth — This is the single most important factor. Plants want consistent warmth and resent cold, damp conditions; they are best kept well above freezing year-round and are happiest with warm nights. Many growers lose plants to a combination of cold and residual moisture in winter.
Soil — Use a very open, mostly mineral mix with generous grit or pumice, in a pot that dries quickly. Shallow, wide containers suit the spreading habit.
Water — Water sparingly during warm active growth, always letting the mix dry out completely in between, and keep the plant dry through the cool season. See Watering for general technique.
Light — Give bright light with some protection from the fiercest afternoon sun; strong light brings out the purple tones in the stems but scorching can damage them.

Because own-root plants are so prone to rot, many growers keep Edithcolea grafted onto a hardier, more vigorous stapeliad rootstock. Grafted plants are markedly easier to keep and flower, and are the usual way collectors maintain the genus long-term. See Repotting when moving plants on, and handle the brittle stems gently.

Propagation

Propagation is possible from stem cuttings, but this is where the plant's temperament shows most clearly: cuttings are slow and reluctant to root and rot easily before they establish. Take cuttings in warm conditions, allow the cut surface to callus well, and set them barely into a dry, gritty medium, keeping them warm and only just moist. Success rates are often low, which is a large part of why grafting is so popular for this genus. Seed is also used where available. See Propagation - cuttings and Propagation - seed for general method.

Notable species

In practice the hobby treats Edithcolea as a single, variable species:

Edithcolea grandis — the Persian carpet flower, the one species you are almost certain to encounter, with numerous regional forms differing in flower size, colour intensity and stem robustness across its African and Arabian range.

Various named forms and localities of E. grandis circulate among collectors, prized for particularly bold or richly coloured flowers, but they represent variation within the species rather than distinct species in cultivation.

Common problems

Rot — by far the leading cause of loss, driven by cold, overwatering, or a mix that holds moisture; affected stems soften, discolour and collapse, and the rot can spread quickly through a clump. Remove affected material at once and keep the rest dry and warm.
Cold damage — chilling, especially when combined with damp, causes blackening and dieback; keep plants reliably warm.
Slow, reluctant rooting — cuttings frequently fail before establishing, which is why grafting is favoured.
Pests — mealybugs (including root mealybugs) can lodge in the stem angles and among the roots; see Pests and diseases.

References

Horticultural information for growing these plants as ornamentals. Always confirm plant identification and any handling, grafting, or safety advice against authoritative sources before acting.