Conophytum burgeri
| Light | Bright light with some protection from harsh midday sun; needs strong light to stay compact and well coloured |
|---|---|
| Water | Sparingly, and only during the cool-season growing period; keep bone dry through summer dormancy |
| Soil | Very free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Frost-free; USDA zones 9b–11 |
| Propagation | Seed (primary); the plant is usually solitary, so offsets are rarely available |
| Toxicity | Not known to be toxic to cats or dogs |
Conophytum burgeri (Burger's onion) is a highly sought-after, largely solitary member of the genus Conophytum from the arid Bushmanland region of South Africa. It forms a single, almost perfectly spherical body of glassy translucent tissue that flushes red-green in strong light, so that a well-grown plant looks remarkably like a polished gemstone or a small, glowing onion — a resemblance that has made it a prize among collectors.
Description
Conophytum burgeri consists of a single, rounded, dome-shaped body a few centimetres across, without the paired-lobe or bilobed shape seen in many other Conophytum species. Older plants may occasionally divide over several years into two or three heads, but the plant is usually solitary. The skin is smooth and unusually translucent, patterned with a fine network of darker "windows" and veins through which light passes into the plant's interior. In bright conditions the body takes on a deep reddish tone over a green base, giving it its jewel-like, semi-transparent appearance; in weaker light it stays greener and can lose the prized colour.
Like other conos, the plant grows a fresh body each season inside the sheath of the old one, which dries to a papery skin. Flowers appear from a small slit at the top of the body in autumn, and in this species they are day-opening and typically pale pinkish- to rose-purple, often honey-scented.
Distribution and habitat
The species is a narrow endemic of Bushmanland in the Northern Cape of South Africa, known from a very restricted area near Aggeneys, where it grows on exposed raised flats of rocky, quartz-strewn ground in an extremely arid climate. Plants sit low among pale stones, their translucent bodies well suited to catching light while the veiled interior is shielded from the fiercest sun. Unusually for the genus — most Conophytum come from winter-rainfall areas — its habitat receives what little rain it gets mainly in the warmer months, and the plants are thought to depend heavily on winter fogs and dew that condense on the surrounding rocks.
Because it occupies such a limited range, C. burgeri is highly vulnerable to over-collection and habitat disturbance; it is assessed as Critically Endangered on the IUCN Red List, with wild populations under heavy pressure from illegal harvesting for the succulent trade. As with all cultivated succulents, nursery- and seed-raised plants are the responsible way to grow it; wild collecting is not.
Cultivation
Conophytum burgeri is treasured but demands respect for its seasonal cycle, and getting the watering rhythm wrong is the usual cause of loss. Grow it in a small pot of very gritty, mostly mineral mix in the brightest light you can give it short of scorching — strong light is what keeps the body compact and brings out the red colouring.
In cultivation it is almost always grown on the standard cool-season Conophytum cycle, regardless of its unusual wild rainfall pattern. Water during the cooler growing months when the plant is plump and active, allowing the mix to dry between drinks, and then keep it completely dry through its hot summer dormancy, when the old body dries to a protective papery sheath. Watering a dormant plant in summer heat is an easy way to rot it. See Watering and Repotting for general technique, and repot only during the growing season if needed.
Propagation
Seed is the main method of propagation. The fine seed is sown onto a gritty, mineral surface and kept humid and cool during the growing season until it germinates; seedlings are slow and need patient, careful watering. Because C. burgeri is characteristically solitary and does not readily form clumps, division and offset propagation are seldom an option, so seed-raising is how most plants in cultivation are produced. See Propagation - seed for a full walkthrough, and Propagation - offsets for the clumping conos where that method applies.
Common problems
- Rot — usually from watering during summer dormancy or from a mix that holds too much moisture; the body goes soft and translucent-mushy rather than firm.
- Loss of colour and swelling — too little light leaves the body pale green and over-plump instead of compact and ruby-toned.
- Failure to shed the old sheath — with poor light or an off watering cycle the old skin can trap the new body; grow harder and drier to keep the cycle clean.
- Pests — mealybugs (white fluff at the base and in crevices) and, under glass, sciarid fly larvae in an overly damp mix are the usual troubles.
See also
- Conophytum — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation - seed · Propagation - offsets · Pests and diseases