Coryphantha bumamma
| Light | Bright light with some protection from the harshest afternoon sun |
|---|---|
| Water | Regularly in the growing season once the mix is dry; keep dry and cool in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed; occasional offsets |
| Toxicity | Not known to be toxic to cats and dogs |
Coryphantha bumamma is a globular Mexican cactus prized for its unusually large, fleshy, rounded tubercles and its big, showy yellow flowers. Closely related to (and sometimes treated as a subspecies of) Coryphantha elephantidens, it forms a low, blue-green dome of swollen bumps that give the plant a soft, sculptural look quite unlike the spiny cushions of many of its relatives.
Description
Coryphantha bumamma is usually solitary, forming a flattened to rounded body up to about 13 cm across. Its most distinctive feature is its tubercles: very large, broad, rounded and fleshy, arranged in a loose spiral over a blue-green to grey-green body. A woolly groove running along the upper side of each tubercle, and the abundant wool in the axils, are typical of the genus.
The spination is comparatively modest for such a robust plant — a small cluster of curved, greyish radial spines per areole and no central spine, so the overall impression is of a smooth, bumpy dome rather than a fierce one. Large funnel-shaped flowers, clear yellow and sometimes with a reddish midstripe, open from near the crown in summer, followed by greenish fruit. Like other members of the genus it stores water in those swollen tubercles, contributing to its chunky, drought-adapted appearance.
Distribution and habitat
The species is native to Mexico, where it grows in the warm, seasonally dry scrub and hillsides of the country's central and southern states, including the region around Guerrero. Plants typically root in rocky or gritty ground among low shrubs and grasses that offer light shade and sharp drainage. The climate is marked by a distinct summer rainy season and a long, dry, cooler winter — a rhythm worth imitating in cultivation.
Cultivation
Coryphantha bumamma is a rewarding grower that appreciates a little more water than many desert cacti during its active season, reflecting its fleshy, water-hungry tubercles. Grow it in a very free-draining, mostly mineral mix in a pot that gives the roots a little room, and give it bright light with some shade from the fiercest afternoon sun to keep the body firm and well-coloured.
Water thoroughly through spring and summer once the mix has dried, then taper off in autumn and keep the plant dry and cool over winter. This winter rest both hardens the plant against rot and encourages the following season's flowers. Protect from frost. See Watering and Repotting for general technique.
Propagation
Seed is the usual and most reliable method: sow on a warm, gritty surface kept humid until germination, then grow the seedlings on slowly in a lean, mineral mix. Mature plants occasionally produce offsets that can be removed and rooted, though the species is not a prolific clumper, so vegetative increase is limited. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — the commonest cause of loss, almost always from overwatering, a slow-draining mix, or standing water in winter; the plant softens and discolours from the base or crown.
- Etiolation — too little light makes the body pale and stretch, losing its neat, low profile.
- Pests — mealybugs (white fluff tucked among the tubercles and in the wool) and root mealybugs are the usual culprits, with red spider mites possible in hot, dry, stagnant air. See Pests and diseases.
See also
- Coryphantha — the genus overview
- Coryphantha elephantidens — the closely related, larger-flowered species
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets