Chamaecereus
Chamaecereus is a small, monotypic cactus genus from the mountains of northwestern Argentina, raised for the peanut cactus — a low, freely branching plant whose finger-like stems cluster into dense mats. Modern botanists fold it into the large genus Echinopsis (as Echinopsis chamaecereus), but the name Chamaecereus remains firmly in everyday use among growers, and the plant is one of the easiest and most floriferous cacti a beginner can keep.
Description
The peanut cactus produces short, soft-spined stems that are typically finger-thick, sprawling and offsetting so freely that a mature plant becomes a tangled cushion of green "peanuts." The stems are ribbed and carry many fine, bristly white spines that are soft enough to handle without much fuss. Individual segments detach very easily — a trait that makes propagation almost effortless.
In late spring and early summer the plant can flower prolifically, opening funnel-shaped blooms along the stems. In the wild species the flowers are a vivid scarlet-orange, but decades of hybridising have produced a wide spectrum of colours in cultivation (see below).
Distribution
Chamaecereus is native to the high grasslands and rocky slopes of the Tucumán and Salta provinces of northwestern Argentina, where it grows at altitude among rocks and low vegetation. This montane origin gives the plant real cold tolerance for a cactus and a natural preference for a cool, dry winter rest.
Notable species
Because the genus is monotypic, it contains a single accepted species, though you will encounter it under several names:
- Chamaecereus silvestrii — the peanut cactus itself, now more correctly written Echinopsis chamaecereus. Also long sold simply as Chamaecereus silvestrii.
Much of what is grown and traded under the Chamaecereus name is not the pure species at all but its many garden hybrids, which cross the peanut cactus with larger-flowered Echinopsis and Lobivia relatives.
Cultivation
The peanut cactus is famously forgiving and a superb first cactus. Grow it in a gritty, free-draining mix in a bright spot; a few hours of direct sun encourage the best flowering and keep the stems compact, while too little light makes them thin and floppy. Water generously through the warm growing season, letting the mix dry between soakings, and then keep the plant cool and almost completely dry over winter. See Watering for the seasonal rhythm.
That cold, dry winter rest is the single most important thing for flowers: kept cool and dry, plants set buds reliably in spring, whereas a warm, watered winter usually gives lush growth but few blooms. The species is hardier than most cacti and can take a light touch of frost if bone dry, but it is safest treated as tender. Being a vigorous clumper, it appreciates repotting every year or two into a slightly wider pot or shallow pan.
Hybrids and cultivars
The peanut cactus has been hybridised extensively, and much of its popularity rests on these crosses rather than the wild plant. Hybrids typically keep the easy-going, clustering habit while offering much larger flowers in yellows, pinks, oranges, reds and near-whites. A well-known oddity is the yellow, chlorophyll-free form Chamaecereus 'Lutea' (sometimes labelled f. lutea), which cannot photosynthesise for itself and is therefore maintained by grafting the coloured segments onto a green rootstock. As with any colourless or heavily variegated cactus, such plants depend entirely on their stock and cannot be grown on their own roots.
Propagation
Few cacti are simpler to multiply. Segments break off at the lightest touch; laid on dry soil to callous for a day or two, they root within weeks and quickly form new clumps — see Propagation — cuttings and Propagation — offsets. The species and its hybrids can also be raised from seed, and seed is the usual route when breeders are chasing new flower colours.
Common problems
- Etiolation — in too little light the stems grow thin, pale and lax instead of plump; move to a brighter position.
- Rot — the usual result of a wet, cold winter or a soggy mix; keep plants dry during their rest.
- Pests — mealybugs love the crowded gaps between stems, and red spider mites may appear in hot, dry, stale air. See Pests and diseases.
See also
- Echinopsis — the genus into which Chamaecereus is now merged
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Propagation — offsets