Glossary

To move a plant to brighter light, drier air or colder weather gradually, in small steps, so it has time to adjust. Every light change has to be gradual; a single week's swing from cloudy and 80°F to sunny and 95°F is enough to burn a plant.

Air spaces in the soil. Roots need air as well as water, which is why gritty, chunky soil grows better cacti than dense soil.

A fabric or perforated plastic pot that lets air reach the sides of the root ball. Reported to produce more roots during the rooting stage.

A seedling born with no green pigment at all. It emerges pure white and dies within a week or two unless it is grafted onto a green plant that can feed it.

A fungal disease that shows as banded light-and-dark patches, or rings of tan and dark colour, on the skin — and the patches can crack open. It leaves permanent scars and is dangerous if it reaches below the soil line.

The fuzzy part inside a flower that carries the pollen.

The plant's habit of putting all its growth into the single tip at the top. Cutting that tip off releases the plant to make side branches instead.

The small felt-covered spot on the rib where spines, flowers, fruit and new branches all come from. New growth can only start at an areole, so the number of areoles on a piece sets the maximum number of new branches it can make.

Tying a fine mesh bag over a flower bud before it opens, so insects cannot bring pollen you did not choose. It comes off to hand-pollinate and goes straight back on, and stays on until the flower wilts.

Sold or shipped with the soil washed or shaken off the roots. Common for rooted plants and seedlings, and normal rather than a problem.

At or near the base of the plant. "Basal pups" are new branches coming from low down; "basal rot" is rot starting below the soil line.

To trim the outer edge of a cut face at an angle so that only soft inner flesh, and no tough outer skin, meets the other piece in a graft.

"Buy it now." In community sale posts, a fixed price you can claim by commenting, rather than bidding.

A fungal disease that attacks the growing tip, turning it into a wet black mess. Its purple-black colour is what tells it apart from ordinary brown rot.

Standing a pot in a tray of water so the soil draws it up from below, instead of pouring water on top. Preferred where pot size allows.

One of the main species in this group, also called Bolivian Torch. Usually few ribs, widely spaced areoles and often long needle-like spines.

A plant shedding buds before they open. Usually a dry spell while it was budded — or a cutting working out that it cannot support all of them and cutting its losses early.

Constantly making new heads instead of growing one tall column. Each head grows at normal speed, so the plant gains bulk several times faster than a single-stemmed one.

The hard, dry, shiny scab that forms over a fresh cut as it heals. A cutting must have one before it is planted, or the wet wound rots in the soil. How long it takes is set by how thick the piece is, not by the calendar: allow about a week of drying for every inch of stem thickness, which works out at two to three weeks for an ordinary cutting, a few days for a slim pup, and longer again for a fat column. The finished face is what tells you, and you will never be early. Drying too long costs nothing — drying too little costs the cutting.

To shave the sharp top edge off a flat cut. As the wet flesh dries it shrinks, and a flat cut turns into a shallow bowl that collects water and rots; chamfering stops that.

Yellowing of the whole plant caused by a nutrient shortage rather than by sun.

One original plant and every piece ever cut from it. Cut a plant in two and both halves are the same clone. Because these cacti cannot pollinate themselves, a clone can only be copied by cutting or grafting — never by seed.

The natural change from green skin to brown, bark-like tissue, normally starting at the base as a plant ages. It also happens wherever something rubs the plant. It is not a disease.

One of the two little horn-shaped first "leaves" a cactus seedling emerges with, before it grows any spines.

A growth form where the single growing point stretches into a line instead of a point, so the plant grows in wavy fans that look brain-like or coral-like.

Seed made by putting pollen from one plant onto the flower of another. Written mother × father.

A named variety that people deliberately bred or selected, as opposed to one that turned up in the wild.

The seller takes the cutting off the mother plant only after you order it, so the drying time happens after you pay. Reckon on about a week of drying for every inch of stem thickness: two to three weeks for an ordinary cutting, and longer for a fat one.

A piece cut off a bigger plant and rooted as a plant of its own. It is not a seedling and it is not a baby: it is the same plant as the one it came off, the same age genetically and the same clone, which is why a cutting is the only way to buy a named plant and get exactly that plant.

Cutting a grafted top off its rootstock so it can grow on its own roots. Needed on thin-stemmed rootstocks that cannot hold the weight; not needed on a Trichocereus rootstock.

The rest period when a plant stops growing. It is triggered by cold — growth stops when daily highs stay below about 60°F, and the main trigger is temperature below roughly 55°F. Plants also go dormant in extreme heat. It is not required to keep a plant alive.

A meter reading of how much fertiliser is dissolved in water. Preferred over parts per million, because that unit has several competing conversion standards and meters work it out from conductivity anyway.

The other genus name these plants get filed under. A 1974 revision moved Trichocereus into Echinopsis, a long line of later botanists declined to follow it, and that refusal — not confusion — is why both names are still in print: the same plant is Trichocereus bridgesii on one label and Echinopsis lageniformis on the next. The current treatment this library follows keeps Trichocereus as a genus of its own.

The plant's skin.

The second half of a two-word botanical name: the pachanoi in Trichocereus pachanoi. It is the part that can move when the botany is revised — pachanoi now sits as a variety under the older name macrogonus — which is why one plant can honestly carry two names. (M — taxonomy is contested)

New growth that comes out noticeably thinner than the rest of the stem. On a rooted plant it means too little light; on an unrooted cutting it means the tip is not getting enough water and food yet. The thin section never thickens back up — it stays a permanent weak spot.

The powdery blue-grey bloom on the skin of some plants. Shade and short daylight hours bring more of it out; full sun bleaches it off. It rubs off permanently, so oils, sprays and scrubbing destroy it.

Soil that holds as much water as it can without any pooling or dripping — damp, not wet. The target moisture for germinating seed.

A collector's number instead of a name: initials and a figure, like BK10805.1. The letters are whoever collected the plant, the number is their own record of that collection, and neither tells you anything about how the plant looks. Names built this way are a different kind of label from a nickname somebody gave a plant they liked.

Spraying diluted nutrients onto the plant's skin instead of watering them into the soil. Only works at night, because a cactus's pores are shut during the day.

A stretch of stem that temporarily grows only four ribs instead of the usual six to eight. It is something a plant does, not a variety — though one cultivar is also called Four Winds.

Whether a pollinated flower actually goes on to make a fruit. You know about two weeks later: the flower shrivels while the green base behind it swells. A failure drops the whole flower, base and all, with nothing left on the rib.

A seed coming to life and pushing out its first root. With fresh Trichocereus seed most of it happens between about day 4 and day 14, and stragglers keep appearing for weeks afterwards.

Covered in a blue-grey powdery coating. It is the word growers use for a plant carrying a lot of that bloom.

Two cacti joined so one plant's roots feed another plant's top. Held together by pressure alone — nothing is glued or added between them.

Growers' informal word for the areole — the felted spot the spines come out of — used in the phrase "seagulls over growholes".

Moving pollen from one plant's flower onto another's yourself, with a cotton swab or a small brush, rather than leaving it to insects. On many sites it is the only way fruit sets at all, even with plenty of bees about.

Slowly getting a sheltered plant used to real conditions — more light, drier air, more wind — by increasing exposure in small steps over weeks.

A disposable warmer added to a shipping box in cold months so the plant does not freeze in transit. Usually a paid extra.

A raised bump on the skin that appears when the roots push in more water than the skin's pores can breathe out. Sometimes skin-coloured, sometimes turning black. Caused by wetness plus poor airflow, not by infection.

A powder or gel sold to speed up root formation. Strictly optional: these cacti root readily without it. If you do use it, powder on a fresh wet cut does far more than gel on an already-dried one — on a finished callus it is mostly decoration.

The mineral, non-rotting part of a soil mix — pumice, lava rock, perlite, grit. Its job is air, drainage and stopping the mix compacting.

"In search of." A post asking to buy something rather than offering it.

A population of plants from one wild place, rather than one named plant. Growers catalogue landraces separately from named clones, and two landrace seedlings from the same place will still be different individuals.

A plant's parents, and their parents. Only crosses have one: a named clone is a cutting line, so it has an origin rather than a pedigree, and plenty of well-known names have no recorded parents at all. Where nobody wrote the cross down, the honest answer is that the lineage is unknown — not a guess that looks tidy.

When soil chemistry, usually the wrong pH, stops a plant taking up a nutrient that is physically present. The plant shows a deficiency even though the food is right there.

Laying a stem down horizontally and half-burying it. It roots along its whole underside and throws pups all up its length, which is exactly how broken pieces spread in the wild.

A species name for stout, blue, well-spined plants. Under recent formal revisions it is the older name, and therefore the official one, that much of "pachanoi" and "peruvianus" would fold into — but the hobby still uses all three.

A sap-sucking pest that looks like small patches of white sticky cotton wool around areoles or in the roots. It moves, so it spreads faster than scale, and it can carry witch's broom between plants.

The growing point at the very tip, where new stem is made. If a pest destroys it, the tip stops and the plant branches instead.

A section taken from the middle of a column, with no growing tip on it. It restarts as new pups from its areoles. It roots and grows just as well as a tip, and it cannot etiolate at a tip because it has none. It must be planted the right way up.

A growth form where the plant grows in strange, irregular, lumpy or melted-looking shapes instead of neat ribbed columns. Many monstrose plants switch back and forth between normal and strange growth over their lives.

The established plant that cuttings are taken from. Also, in a cross, the plant that carried the fruit.

Beneficial fungi that partner with roots and improve water and nutrient uptake. Both Trichoderma products and strong synthetic fertiliser kill them, so pick one strategy — you cannot run them together.

A different genus that turns up in the same collections. Worth knowing because its crested form is routinely mistaken for a crested monstrose bridgesii, and the two are not the same plant or the same price.

"No ID." A plant with no known name. Sold and bought openly as a budget category, at roughly a third less than named plants.

The three numbers on a fertiliser label: nitrogen, phosphorus, potassium. Nitrogen drives green growth, phosphorus drives roots and flowers, potassium drives strength and disease resistance.

A fast-growing plant deliberately grown next to a young cactus to shade it, then cut away once the cactus can take full sun.

See humidity blister.

Seed where the mother is known — the fruit grew on her — but the pollen father is not, because bees got there first. One open-pollinated fruit can hold seeds from several different fathers.

The part of a soil mix that was once alive — compost, humus, worm castings. Its job is to hold water and food.

The swollen base sitting behind a flower. If pollination worked, this is the part that becomes the fruit; if it did not, the whole flower drops away and takes it with it.

Growing on its own root system, as opposed to grafted onto another plant. Worth stating on a listing, because some clones look and grow completely differently the two ways.

The species most people mean by "San Pedro". Usually six to eight broad rounded ribs, short sparse spines and matte green skin.

The single clone that makes up the overwhelming majority of San Pedro sold in North American nurseries and garden centres. Every PC plant is a piece of one original plant, so it cannot make more of itself from seed. It is tough, fast and cheap, which is why it is the standard rootstock.

A thin, leafy, fast-growing cactus used as grafting stock for seedlings. A seedling grafted onto it reaches a size in a year that would otherwise take several, which is why almost every early hybrid you see offered has been on one. It wants far more water than a Trichocereus does, so it is stock, not a houseplant.

The white popcorn-like mineral in bagged potting mixes, used to make soil drain faster. Cheap, light and everywhere, and it works — but it floats to the surface over time and holds more water than it looks like it should. Pumice does the same job without either habit, which is why it is the upgrade.

A species also called Peruvian Torch. Longer, stouter spines than pachanoi and often a strong blue bloom. Has many regional forms named after where they came from.

How acid or alkaline the water and soil are. Out of the right range, a plant cannot absorb food that is physically present. Target feed pH is 5.5–6.5.

What a plant actually looks like, as opposed to what genes it carries. The same clone can show different phenotypes in different climates.

A bacteria-like organism spread by sap-sucking insects. The cause of true witch's broom. Not curable.

The yellow dust the anthers carry. It is the half of a cross that travels, it loses strength within about a day at room temperature, and it can be dried and frozen for months.

The plant the pollen came from: the father of a cross. In a written cross it goes second, after the ×.

A measurement of how much usable light actually reaches the plant, used for indoor growing. Minimum useful level for mature cacti is about 750; 1000–1250 is much better.

Where a plant came from and whose hands it passed through. Growers here trade the story with the cutting, and for peruvianus especially a plant is often labelled by the place it was collected — Matucana, Rimac — rather than by a clone name. It is the part of a listing that cannot be checked from a photograph.

A full round slice cut across a stem, used as a graft piece. Cut in half and laid on its side it becomes a slab.

A porous volcanic rock used in soil mixes. Heavier than perlite, does not float or crumble, and generally the preferred choice.

A new branch growing out of an areole. It is the plant's normal way of multiplying itself.

Keeping a newly bought plant well away from your others for a period, and inspecting it, before it joins the collection. The commonest way pests enter a collection is on a bought plant.

A monstrose plant that starts producing normal ribbed growth again. Reverts can later go strange again. Young monstrose plants are often mistaken for reverts when they are simply not weird yet.

One of the vertical ridges running up the column. Ribs work like an accordion: squeezed together means the plant is thirsty, spread wide and flat means it is full of water.

Roots that have filled the pot completely and started circling. Slows growth, though it can also bring on earlier flowering.

The rooted bottom plant in a graft: the one supplying the roots.

Soft, squishy, dark tissue. The test is touch: soft means rot; a hard dark patch is not rot. Caused by too wet for too long, too cold, or an untreated infection.

The water that comes out of the drainage holes. A little is needed to flush salts out of the soil; too much washes the food away. Targets given range from about 6–10% to at least 15% when feeding.

A fungal disease showing as reddish-orange specks or patches. Driven by heavy rain plus heavy watering; plants often grow out of it once humidity drops.

The memory trick for which way up a cutting goes. The notch above each areole looks like a seagull's wings, and the gulls should be flying up.

A sap-sucking pest that looks like small white, tan or brown dots stuck to the skin. The test: if it wipes off with a damp cloth or toothbrush, it is scale; if it does not, it is scarring.

The top piece in a graft: the one being carried and fed.

A species with very few ribs, essentially no spines, and glossy green skin with a smooth melted look. Popular as a hybrid parent because it passes on smoothness and vigour.

The plant that carried the flower and the fruit: the mother of a cross. In a written cross it goes first, before the ×.

Unable to make seed with its own pollen. A Trichocereus flower needs pollen from a genetically different plant — a different seedling, not another cutting of the same clone. This is why a named clone can never be reproduced from seed.

Plants grown from seed out of the same fruit. They share parents but not genetics, so they are not copies of each other or of either parent — and unlike two cuttings of one clone, they can cross with each other.

A round slice of stem, cut in half and laid on its side onto the rootstock. One donor piece gives several grafts this way.

A black, soot-like film sitting on the surface, usually in the rib grooves of older growth. The plant underneath is fine and it scrubs off — but scrubbing also removes the blue bloom. Mostly a sign that humidity is high and airflow is low.

A plant's spines taken as one feature — how many come out of each areole, how long they run, what colour they are and how they sit. It is the word entries and catalogue descriptions use when they mean all of that at once rather than one spine.

An insecticide that is the community's first choice for thrips and mites. Applied at dusk, four or five times over, because it kills neither the eggs nor the young stage that waits in the soil.

A tiny harmless insect often mistaken for a pest. If it jumps when you blow on it, it is a springtail — leave it alone.

The central structure inside a flower that receives pollen; it looks a bit like a small octopus.

The lowest piece of a column, cut off above the soil, often already rooted. It is the easiest part of all to grow on: the pups come sooner and bigger than they do on a fresh cutting, because the roots are already feeding them.

Permanent scarring from too much sun too suddenly. It goes yellowing → burn → scar, always worst on the sun-facing side and on the protruding parts of ribs. Different from bleaching, which is a reversible fading.

Laying seed on top of the mix and pressing it down instead of covering it. Cactus seed needs light falling on it to germinate, so burying it is the commonest way to lose a whole tray.

Short for Trichocereus bridgesii monstrose: the lumpy, knobbly, irregular form of Bolivian Torch. TPM is the same idea for pachanoi.

A growing tip that has simply stopped getting longer. It is normal, not damage; the plant pushes a new branch instead. Terminated tips still fatten.

Tiny elongated insects that feed at the growing tip and leave tan, sandpaper-textured scarring. Their eggs are laid inside the plant tissue, which is why one spray never works.

A cutting that includes the growing point, so it carries on growing from that tip. Priced slightly above a mid cut of the same length.

A layer of grit or fine gravel spread over the soil surface. It steadies a fresh cutting, stops soil splashing onto the flesh, and looks finished — but it also slows the soil's drying and hides how wet it is under there. Use it on established plants if you like the look; skip it while anything is still rooting.

Trichocereus pachanoi monstrose: the lumpy, irregular form of San Pedro, and the pachanoi counterpart to TBM. Cuttings off one widely grown monstrose pachanoi line mostly come out looking perfectly ordinary, so the name tells you what the parent was rather than what will turn up in the box.

The group of tall columnar cacti this whole site is about, native to the Andes. The name refers to the hairy flowers and fruit.

Patches or streaks of a second flesh colour — cream, lime or yellow — on one plant. Yellow is the most prized. Variegated plants grow slower because the pale tissue makes less food, and fully yellow tissue usually cannot survive on its own roots.

In hobby usage, the same idea as a clone or a strain: one specific set of genetics.

The circle of conducting tissue you can see in the middle of a freshly cut face. A graft only works if the two rings touch.

Small non-functional nubs where a proper spine or branch would normally be. Recognised as its own visual trait on some clones.

A measure combining temperature and humidity that describes how easily a plant can breathe. When night VPD is too low, a cactus cannot open its pores, cannot exchange gases and stops growing — which is what heat dormancy actually is.

Wildly abnormal clustered growth: a pup on a pup on a pup, each one already pushing more from its own areoles. True witch's broom is a phytoplasma infection: contagious, incurable and eventually fatal. It is easily mistaken for natural monstrose or crested growth — never buy a plant showing it. Pest damage to a growing tip can raise a similar, harmless cluster that clears once the pest is dealt with — so isolate a plant you already own and watch it, but walk away from one you were about to buy.

A seed-grown plant about a year old: past the fragile seedling stage, not yet an adult, and treated as its own stage by anyone raising seed. It takes a coarser grit than a seedling and a finer one than an adult, and buying one saves roughly a year over starting from seed yourself.