The magician’s herbal, in plain English

Cover image: a fifteenth-century Latin Picatrix, Kraków MS 793. Public domain · Wikimedia Commons, cropped

There is a jar of nutmeg in your kitchen, and maybe a bottle of valerian beside the bed. Both turn up in a medieval book of magic, a book that also burns opium over talismans and reaches for birthwort against snakes. We count 153 plant entries in it, and thirteen of the names still cannot be matched to a plant. Some of what it says stands up. One of its remedies is a plant that wrecks kidneys and causes cancer.

The book is the Picatrix. This is the short version of our full essay on it, for herb users with no time for footnotes.

Educational content only. Nothing here recommends obtaining, preparing, burning or taking any plant named on this page. Several are poisonous, some are controlled, and some are prohibited from use in medicines in Australia.

What the book is, and what it does with plants

Planet labels that turn out to be taste and smell.

The Arabic title is Ghayat al-Hakim; Europe called it the Picatrix. Its planetary lists look arbitrary until you taste them. Saturn takes the bitter and foul: hemlock, colocynth, opium, mandrake. Mars takes the hot: pepper, ginger, mustard. Venus takes the sweet: rose and mastic.

The labels are planets. The hand sorting them is Galen’s old scheme of hot, cold, dry and moist, read off taste and smell. Bitterness often flags the defences a plant builds against being eaten. That is the thing worth holding on to. The book is a learned technical work with a manuscript history behind it, and treating it as village superstition misses what it is. The theory it runs on died centuries ago. Some of what it wrote down has outlived the theory.

The book’s standard operation is smoke: storax, frankincense, mastic, myrrh and labdanum, burned at the right hour over a figure. Nobody brews a tea. Most aromatic smoke is better understood as mood and setting than as a drug dose. The exceptions want harder handling. Henbane goes on the fire. Opium goes on the fire. Cannabis turns up in one lunar incense. Those are active materials, and heating a psychoactive or poisonous plant changes the safety question.

Where the old book got it right

Where the body answers fast, the old observations mostly hold up.

The sleep-and-stupor material includes opium, mandrake, henbane, datura, nightshade, poppy, lettuce, darnel and nutmeg. Six of those carry pharmacology nobody needs to romanticise: opioid action, nightshade delirium, sedation, toxicity, plain poisoning. Nutmeg does intoxicate people in reported cases, though what they describe is a poisoning, and how it does it has never been established in humans.

The poisons are plainer. Coniine, from poison hemlock, brings a paralysis that climbs the body. Aconitine holds the body’s sodium gates open so they cannot reset, which is why aconite poisoning can end in a dangerous heart rhythm. And one old name can sit on two different plants: black hellebore and white hellebore are different genera carrying different poisons, which is why a name out of an old book is never an identification.

Where it turns to poetry

Rose, saffron, myrtle: costly, fragrant, chosen for meaning.

When the text turns to love, favour and success with kings, the match with pharmacology thins right out. Rose, saffron and myrtle are fragrant, expensive and heavy with meaning. Chemistry will grant you a pleasant smell. It will never grant a binding agent.

Valerian shows how evidence gets flattened. Its reputation as a sleep herb rests on traditional use, on laboratory work at the brain’s calming switch, and on human trials that disagree with each other. Some support, well short of a clean claim. The Picatrix uses it as a love philtre.

The most dangerous sentence in the book

Birthwort against snakebite, read in Queensland English.

The Picatrix puts round birthwort into a preparation against adders. Aristolochic acids, the compounds in that plant, poison the kidneys and cause cancer; the recorded harms in people include kidney failure and cancer of the urinary tract. That is why birthwort — the whole Aristolochia group of plants — is prohibited from use in medicines in Australia. Against snakebite the plant has never been shown to do anything useful in a human being.

One tradition can hold a correct warning about a poison and a dangerous false remedy side by side on the same page.

One good story before you go

Scammony emptied people out and nobody could say why.

Scammony is a violent purgative. Medieval physicians could see the effect and could not explain it from hot, cold, dry and moist, so they reached for a hidden virtue: a power belonging to the substance itself.

Once that idea exists, a medicine and a talisman become neighbouring claims. We keep those in separate drawers. The compiler kept them far closer together.

Image credits. All images are reused from the parent essay, under the licences the photographers set. Latin Picatrix, Kraków Jagiellonian MS 793, and the Arabic Picatrix, Hamidiye MS 852 — public domain, Wikimedia Commons. Coffee ceremony — ProtoplasmaKid, CC BY-SA 4.0. Opium poppy — Niccolò Caranti, CC BY-SA 4.0. Saffron — Emilie40, CC0. Round birthwort — MurielBendel, CC BY-SA 4.0. Scammony — איתן פרמן, CC BY-SA 3.0. The hero and the section banners are cropped from those originals and nothing else about them has been changed; the cropped versions of the CC BY-SA photographs are shared under the same licence as the originals. Each caption links the licence and the source file.

AIP Explainers are the plain-language editions of the Institute’s technical articles, published alongside the original. Every claim here is carried by the full essay, where the sources, the evidence grades and the regulatory reading are set out. The Australian regulatory position was read on 20/09/2026 and may change; it is the Institute’s published reading and not advice. Found an error? Write to our contact form — we would rather correct a claim than repeat it.