Pachypodium brevicaule
| Light | Very bright light to full sun; keeps its compact shape only in strong light |
|---|---|
| Water | Regularly while in leaf and growth; keep completely dry through winter dormancy |
| Soil | Extremely free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep warm; protect from frost, USDA zones 10–11 |
| Propagation | Seed (primary); grafting for slow or difficult seedlings |
| Toxicity | Sap is generally regarded as an irritant; best kept away from pets and children |
Pachypodium brevicaule is a highly prized dwarf succulent from the highlands of central Madagascar, famous for its flattened, lumpy, rock-like caudex that hugs the ground like a weathered stone. From this squat, silver-grey body it pushes up small clusters of leaves and cheerful bright yellow flowers in the growing season, making it one of the most sought-after and distinctive members of the genus Pachypodium.
Description
Pachypodium brevicaule is unlike almost any other plant in cultivation. Rather than forming a bottle-trunk or column like its relatives, it develops a low, spreading, tuberous caudex that grows outward into an irregular mass of grey to greenish lumps and lobes. Mature plants can spread across a considerable width while staying only a few centimetres tall, so that a well-grown specimen genuinely resembles a lichen-covered rock sitting on the soil.
Each of the rounded knobs is tipped with short spines and a rosette of small, softly hairy leaves that appear during the growing season. The flowers are bright yellow, borne on short stalks just above the body, and are relatively large and showy for such a compact plant. In its dry winter rest the leaves are shed and the caudex sits dormant and bare.
Distribution and habitat
The species is endemic to the central highlands of Madagascar, where it grows at relatively high elevation on exposed granite and quartzite outcrops. There it wedges itself into cracks and shallow gritty pockets among the rock, fully exposed to strong sun and subject to a pronounced wet-and-dry seasonal cycle: warm, moist summers followed by cool, dry winters. Its flattened, ground-hugging form is very much an adaptation to this harsh, windswept, high-light habitat.
Like all Pachypodium, it is listed under CITES and wild collection is restricted; the plants seen in cultivation should be nursery-propagated. Please buy only seed-grown or legitimately propagated stock rather than wild-collected plants.
Cultivation
Pachypodium brevicaule has a reputation as a connoisseur's plant, mostly because it resents being kept wet and cold. Grow it in a very open, mostly mineral mix in a container with excellent drainage, and give it the brightest position you can — strong light is what keeps the caudex tight and rock-like rather than soft and stretched.
The key to success is respecting its seasons. Water regularly once the plant is in active growth and carrying leaves in the warm months, always letting the mix dry between waterings, then taper off as autumn approaches and keep it completely dry and dormant through winter. Standing water, a heavy mix, or moisture during the cold rest period readily leads to rot. Keep it warm and never let it freeze. See Watering and Repotting for general technique.
Because of its slow, unusual growth and sensitivity to root rot, some growers cultivate it grafted onto a more forgiving Pachypodium rootstock; grafted plants grow faster and are more tolerant, though they lose some of the squat character prized in plants on their own roots.
Propagation
Seed is the standard and most reliable method. Fresh seed germinates well on a warm, gritty, mineral surface kept lightly moist and humid, and young seedlings are grown on carefully with the same sharp drainage the adults demand. The species does not readily lend itself to cuttings, so grafting of seedlings is sometimes used to speed up or rescue slow or weak plants. See Propagation — seed for a full walkthrough.
Common problems
- Rot — by far the biggest killer, almost always from a mix that holds too much water or from watering during the cold winter dormancy; the caudex softens and discolours.
- Etiolation and soft growth — too little light causes the body to grow up rather than out and lose its characteristic flat, rock-like form.
- Pests — mealybugs can hide in the leaf clusters and among the lumps of the caudex, and spider mites may attack the leaves in hot, dry, stagnant air. See Pests and diseases.
See also
- Pachypodium — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting · Pests and diseases