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Backyard Cyanide

BY SUZIE PETRYK
March 9, 2025

There's a bushy tree in my backyard with these dark red fruit -- the
kind that makes some primal instinct scream at you across millennia,
but you can't tell if it wants you to eat them or not.

I used a plant app to identify it (like a true horticultural expert):
it's Prunus laurocerasus, or cherry laurel. The most innocent of
names. Apparently a popular landscaping choice given its dense
foliage.

Apparently also a popular source of poison used by the ancient Roman
Emperor Nero to assassinate his enemies.

An image of the top branches of a leafy, bushy tree

My own tree, not producing fruit at the time of writing.

An image of a close-up of leafy branches with a bushel of dark red
fruit.

An example of cherry laurel fruit.

An unwitting victim could drink water from their local well, or from
a glass at a lively dinner, never detecting cyanide distilled from
cherry laurel leaves. This was likely thanks to Locusta, Nero's go-to
poisoner, whom he freed from prison after she poisoned his
step-father (why let talent go to waste?). Historians speculate on
her exact arsenal, like deadly nightshade, mushrooms, etc. -- yet
cherry laurel is notable: its leaves, stem, seeds, and unripe fruit
are all toxic,* and cyanide is fast-acting.

I read, aghast, that Locusta was ordered to test a poison "on
children" in preparation for assassinating the heir to the throne.^
[1] Locusta of Gaul - Nero's Notorious Poison Maker. Ancient Rome was
brutal, but poisoning children? I read another source -- "it was then
tried on a kid" -- and kept reading -- "the animal did not die until
the lapse of five hours".^[2]Medical Jurisprudence. Paris &
Fonblanque (1823) A goat, she tested on a baby goat. Not that she was
any short of deplorable; she regularly tested on animals, as well as
slaves.

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Fast forward from 54 AD to 1819 -- you'll find the same plant that
sent unfortunate ancient Romans to their convulsive deaths is now
inside custards and puddings at afternoon tea. Cherry laurel leaves
provided cheap almond-like flavor. When carelessly prepared, these
custards could be dangerous, causing five kids (human this time) at
an English boarding school to fall severely ill for three days^[2]
Medical Jurisprudence. Paris & Fonblanque (1823) -- never thought
"dangerous custard" would be two words I'd write together, as if
they'd describe a villain in an Agatha Christie novel.

Incompetent cooks aside, it was still generally known that cherry
laurel was risky to eat. A book from 1837, grandiosely titled "Two
Thousand Five Hundred Practical Recipes in Family Cookery"^+,
includes a recipe that uses a laurel leaf. It's immediately followed
up with some Victorian-era sass: "Note. -- It might be supposed that
this dish was [invented for] the express purpose of giving trouble;
the laurel leaf is poisonous." ^[3]Two Thousand Five Hundred
Practical Recipes in Family Cookery. Jennings (1837)

An image of an old blue glass bottle with a cork and label that
describes 'Cherry Laurel Lotion'.

Who wouldn't rub cyanide on their eyes to treat eye strain? ^[4]
Cherry-Laurel Lotion. National Museum of American History

So, not to eat, then. But shaving cream? Shampoo? Facial cleanser?
"Cherry laurel lotion" could do the trick, apparently having soothing
qualities. Surely, nothing says "self-care" quite like slathering
diluted cyanide on your face.^[5,Splash it all over: A brief history
of aftershave. Withey (2016) ^6]Instructions and cautions respecting
the selection and use of perfumes, cosmetics and other toilet
articles, with a comprehensive collection of formulae and directions
for their preparation. Cooley (1873)

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Today, you're not likely to find cyanide in your custards or shaving
cream. You might, however, find it in your Sunday dinner -- like the
two Italians who had mistaken cherry laurel for bay leaves and ended
up in the hospital, after eating a slightly almond-y guinea fowl.^[7]
Piante velenose della flora italiana nell'esperienza del Centro
Antiveleni di Milano. Banfi et al. (2012)

They weren't alone; 147 Italians from 1995-2007 had similar
experiences,^[8]Risk of Poisoning from Garden Plants:
Misidentification between Laurel and Cherry Laurel. Malaspina et al.
(2022) along with many an unfortunate grazing animal. Centuries after
Locusta's experiments, goats still have it rough, occasionally dying
from eating cherry laurel leaves.

An image from a paper of four similar-looking leaves.

Spice, or poison? Bay leaves (A & B) look too similar to cherry
laurel (C & D). ^[8]Risk of Poisoning from Garden Plants:
Misidentification between Laurel and Cherry Laurel. Malaspina et al.
(2022)

There's also this gardener, who had a close call:

[A] correspondent told me about the time he filled his car with
bagged shreddings from his large cherry laurel and set off for the
[trip]. On the way, he could smell almonds and thought 'Hmmm, cake!'
before realising what he was smelling. He opened all the car windows
and suffered no ill effects (other than the disappointment of not
having any cake).

Source: The Poison Garden ^[9]The Poison Garden.

So, beware suspicious bay leaves, beware Roman emperors who employ
poisoners, and beware unexpected games of "Is it cake?".

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Despite all the above (the assassinations, the hospitalizations, the
dead goats), part of the cherry laurel is actually edible. You can
eat the fruit as long as it's ripe.^SS Travel to the Black Sea region
of Turkey, and you'll find cherry laurel fruit (or karayemis) in many
different forms -- fresh, dried, roasted, pickled, salted, in jams or
cakes, and more.^[10,An Unsung Prunus. Potentilla (2023) ^11]An
Important Genetic Resource For Turkey: Cherry Laurel. Yazici et al.
(2011)

An image of two jars of dark red jam, with fresh cherry laurel fruit
in front.

Turkish jam made from cherry laurel fruit.

Supposedly they taste kind of like cherries, sour and sweet, and
slightly bitter/astringent/sharp -- basically all of the adjectives.
If you can describe it better than the Internet, let me know. Too
bitter, though, and you'd better spit it out to avoid larger
concentrations of cyanide.

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Crushing a leaf from the tree in my backyard, I don't smell much
other than crushed plant -- no distinctive almond scent. Makes me
wonder if I'm one of the unlucky 20-40% of humans who can't smell
cyanide,^[12]Medical Management Guidelines for Hydrogen Cyanide or if
my backyard has, in fact, no connection to Ancient Rome at all. Can't
tell which of those is worse.

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^* For the pedantic fanbase: technically cherry laurel doesn't
contain cyanide in its natural state, but cyanogenic glycosides,
which can release hydrogen cyanide if the plant is damaged or
digested.^[0] Prulaurasin content of leaves, kernels and pulps of
Prunus lauracerasus L. (Cherry Laurel) during ripening. Demirbolat &
Kartal (2018) -

^+ Actually, if you're curious, the full title is "Two thousand five
hundred practical recipes in family cookery: in which the whole art
of preparing food and drink for the human stomach is simplified and
explained, in accordance to the best knowledge of the age, and most
conducive to the health and happiness of our species: with an
introduction on the duties of cooks and other servants, observations
on the implements employed in cooking, instructions for marketing,
for trussing, and for performing the honours of the table with grace
and propriety in the whole art of carving" ^[3]Two Thousand Five
Hundred Practical Recipes in Family Cookery. Jennings (1837) -

^SS Please, trust unqualified strangers on the Internet for all your
poisoning queries. -

Citations

^[0] Prulaurasin content of leaves, kernels and pulps of Prunus
lauracerasus L. (Cherry Laurel) during ripening. Demirbolat & Kartal
(2018)

^[1] Locusta of Gaul - Nero's Notorious Poison Maker.

^[2] Medical Jurisprudence. Paris & Fonblanque (1823)

^[3] Two Thousand Five Hundred Practical Recipes in Family Cookery. 
Jennings (1837)

^[4] Cherry-Laurel Lotion. National Museum of American History

^[5] Splash it all over: A brief history of aftershave. Withey (2016)

^[6] Instructions and cautions respecting the selection and use of
perfumes, cosmetics and other toilet articles, with a comprehensive
collection of formulae and directions for their preparation. Cooley
(1873)

^[7] Piante velenose della flora italiana nell'esperienza del Centro
Antiveleni di Milano. Banfi et al. (2012)

^[8] Risk of Poisoning from Garden Plants: Misidentification between
Laurel and Cherry Laurel. Malaspina et al. (2022)

^[9] The Poison Garden.

^[10] An Unsung Prunus. Potentilla (2023)

^[11] An Important Genetic Resource For Turkey: Cherry Laurel. 
Yazici et al. (2011)

^[12] Medical Management Guidelines for Hydrogen Cyanide