Pups, cresting and monstrose forms

Some of the most valuable cacti in this hobby look, frankly, wrong. Melted, lumpy, brain-like, growing in fans instead of columns. Collectors pay a premium for exactly that. But one thing that looks very similar is a contagious disease, so this is a distinction worth being able to make with your own eyes.

A pup — what Pup means is a new branch, and it can only start at an areole — what Areole means. That one fact sets the ceiling on everything else: a piece carrying six areoles can make about six branches, however well you grow it.

Cutting — what Cutting means the growing tip breaks the plant's habit of pushing everything into that single point, and it answers by branching instead. A cut typically returns two or three heads; one eight-inch tip taken off a plant returned five pups at the top and five more from the base. Damage does the same thing — a thirteen-foot column that collapsed pupped prolifically from the stump — what Stump (base cut) means it left behind.

A tip that stops extending has terminated. It is normal, it carries on fattening, and the plant simply branches instead.

The most useful thing a buyer can know here is that these forms are not fixed.

Monstrose — what Monstrose means plants alternate between normal and weird growth across their lives. Many look entirely ordinary at first and only start doing anything odd once they have a year or two behind them, so an owner calling a young plant a revert — what Revert means is often just looking at juvenile growth. There is even such a thing as a non-displaying monstrose: one grower only discovered that an ordinary-looking pachanoi — what Pachanoi means carried the genes when about half its seedlings came out monstrose.

Damage can trigger it too. A slug or a sucking bug can leave one clone — what Clone means with shifted ribs, skipped areoles and little nubs, while another clone just scars over and carries on as before. And grafting — what Graft means changes the expression again, so the same clone can be a normal column on stock — what Rootstock (stock) means and a lumpy mess on its own roots — what Own roots means.

Long form and short form of monstrose bridgesii — what Bridgesii means are listed as two things and priced as two things, whatever the genetics eventually settle. Why the long form costs more is not in question: it carries hardly any areoles, and since new branches start nowhere else, each plant offers almost nothing to propagate from.

Variegated — what Variegation means plants grow noticeably slower, especially while they are establishing, and variegation can appear progressively on a plant that looked completely ordinary. Fully yellow tissue has poor odds on its own because it has no chlorophyll to feed with, which is why variegated and low-chlorophyll clones are usually kept on a green rootstock. Albino — what Albino means seedlings come up pure white and die within a week or two.

Witch's broom — what Witch's broom means looks like a spectacular monstrose and is a contagious infection.

The tell is a pup on a pup on a pup — every areole of each new pup already pushing another one out. Alongside that: ribs reduced or missing altogether, miniature dense spines buried in excess wool, and the skin — what Epidermis means going yellow to red as growth outruns what the plant can supply. The cause is a phytoplasma — what Phytoplasma means spread by sap-sucking insects, mealybugs — what Mealybug means among them. It cannot be cured, it spreads, and it eventually kills the plant. Do not buy one.

One caveat before you condemn a plant you already own: there are benign lookalikes. Pest damage to the growing tip can terminate it and force a dense cluster of pups that clears up once the pest is treated, and certain genetic lines throw clustered growth naturally. What the lookalikes do not do is keep stacking — pup on pup on pup with the ribs dissolving is the disease's signature, not a phase.

While you are looking closely, one more mark worth recognising. Where one cactus has jabbed another, the scars come in a line or a cluster, and that pattern is what tells you the damage was mechanical rather than a disease. A mark that scrapes off is probably pest or debris; one that will not scrape off is old scarring.