Cereus repandus 'Monstrose'
Cereus repandus 'Monstrose is a monstrose cultivar of the Cereus repandus, the Peruvian apple cactus, grown for its strange, lumpy, disorganised growth rather than the tall, clean columns of the ordinary plant. Instead of orderly ribs marching up a straight stem, it piles up into irregular knobs, bulges and fused clustering growth — a look that has made it a common and inexpensive novelty in collections.
The "monstrose" habit is a stable growth mutation in which the plant's growing points multiply and grow in a disorganised way, so the stem never settles into a single tidy column. It is sometimes confused with crested (fasciated) forms, but the two are distinct: a crest fans out into a flattened, brain-like ridge, whereas this monstrose form lumps up in three dimensions into rounded, bumpy masses. Because the older name for the species, Cereus peruvianus, is still widely used in the trade, this plant is frequently sold as Cereus peruvianus monstrose or monstrose apple cactus.
Description
The plant forms bluish to grey-green stems that break up into irregular, lobed segments rather than continuous ribbed columns. Ribs are indistinct or interrupted, and the surface is broken by bumps, folds and randomly placed areoles bearing short spines. Growth is unpredictable — some stems bulge and cluster tightly, others send up short, semi-normal columns before reverting to the lumpy habit. Over time a well-grown plant builds into a characterful, boulder-like mound of fused growth.
Like the parent species it is capable of flowering once mature and large, producing the same large, night-opening white flowers, though monstrose plants are grown chiefly for their form and flower less reliably than the ordinary type.
Cultivation
Care is as for the parent species, Cereus repandus. Grow it in a fast-draining, mostly mineral mix, give it as much bright light as you can, and water thoroughly only once the soil has dried out, keeping it dry and cool through winter. It is one of the tougher, faster-growing columnar cacti and tolerates a range of conditions, which is part of why the monstrose form is so widely circulated.
A few notes specific to the monstrose habit:
- Light matters for form. Strong light keeps the growth compact and pronounces the lumpy character; in poor light the plant tends to etiolate, stretching into thinner, paler, less strongly monstrose growth.
- Watch for reversion. Monstrose stems sometimes throw normal columnar growth. If you want to keep the mutant look, you can remove reverting shoots.
- Support and repotting. A large clustered head can become top-heavy; a snug, heavy pot helps. See Repotting for technique.
Propagation
Propagation is vegetative, to keep the monstrose trait: stem sections are cut, left to callus, and rooted as cuttings. Seed is not used, as seedlings would generally revert to normal columnar growth. Vigorous, easy-rooting Cereus is also a classic grafting stock, and monstrose pieces are sometimes grown grafted to speed them along.
See also
- Cereus — the genus overview
- Propagation — cuttings · Grafting · Soil and potting mix · Repotting