Sign at Alnwick Poison Gardens (photograph by Jo Jakeman)
Compared to fauna, flora and fungi have a pretty mellow reputation where humans are concerned. Unsubstantiated rumors of man-eating pitcher plants aside,
most growing things mind their own business, clean the atmosphere,
lynchpin ecosystems, and provide sustenance for the animals, homo
sapiens included. Some, however, contain deadly poison.
Human beings have discovered which plants are poisonous through
unfortunate accidents, only to turn around and make use of
this knowledge. Just ask Socrates.
Whether growing wild or carefully cultivated, deadly plants can be
found all over the word, often inspiring mythology, folklore, and
devotion that says far more about human beings than it does about
botany.
English Yew (Taxus baccata)
England
England
Churchyard Yew illustrated in Charles Tilt's "Woodland Gleanings" (1853) (via Project Gutenberg)
The long-living
English Yew tree is a shrub-like evergreen found across Great Britain,
including in many church yards and graveyards. Historians believe this
is not an accident, as the trees were likely a part of pagan holy sites
that existed before the churches were built. Both pagans and later
Christians came to associate the tree with the soul and with death, most likely because of its highly toxic properties, and possibly because of its eerie appearance.
Scotland's Fortingall Yew (photograph by Paul Hermans)
Myths about the yew are plentiful.
One story espouses their usefulness in undead prevention because their
fine roots grow through the eyes of the dead, preventing them from
seeing their way to the surface. Another, slightly more romantic tale,
says that two yews entwined were the reincarnation of lovers executed
via yew stakes to the heart. Famous examples of the yew tree include the Ankerwycke Yew, which grows on the grounds of a former convent, and Scotland's Fortingall Yew, which grows in a village churchyard and which some claim is 5,000 years old.
Nearly every part of the tree can be fatal to a human, owing to the
rich amounts of the toxin taxus baccata. On top of that, there is a long
history of people making weapons, including deadly longbows, from the
trees. On the upside, in recent years, the tree has been processed into
medicine, including chemotherapy drugs.
Poison Hemlock (Conium maculatum)
Europe
Europe
Socrates holding a cup of Hemlock (via Library of Congress)
In her book, Wicked Plants,
Amy Stewart tells the story of an unfortunate Scottish tailor who in
1845, eats a sandwich prepared by his children, who had collected the
wild greens themselves. He died a few hours later.
Hemlock growing in Lincolnshire, UK (photograph by Mick Talbot)
The children had likely mistaken poison hemlock for parsley, which it
resembles. It’s roots also happen to resemble carrots and that, too,
has lead to deadly mistakes. It grows as a weed on the roadside, in
drainage ditches, and on the edge of cultivated fields across Europe,
and in England has often been associated with witchcraft. As it did in Socrates's time, it has been used to facilitate human death for millennia. On top of that, there are persistent stories of
it growing beneath the cross during the crucifixion, mythology which is
reinforced by the red speckles which appear on the plant during the
spring (usually right around Easter).
Death Cap Mushroom (Amanita phalloides)
Europe, Asia, and the United States
Europe, Asia, and the United States
According to a 2014 Slate story,
those who lived to tell of eating the aptly named Death Cap Mushroom
say it was the most delicious mushroom they'd ever eaten. The Death Cap —
which is a fungi, not a plant — contains a number of toxins, but looks
nearly identical to the edible Paddy Straw Mushroom. Both species grow
wild in forests across Europe, Asia, and the United States. Because they
form a symbiotic relationship with tree roots, Death Caps are most
often found near hardwood trees like oak and pine.
Warning sign for Death Cap Mushrooms, Canberra, Australia (via AYArktos/Wikimedia)
Thanks to Paddy Straws being popular in many Asian cuisines and the
easy misidentification, the aptly named Death Cap is thus responsible
for the vast majority of mushroom poisoning deaths. Case in point, a couple living on the Isle of Wight picked
some of these mushrooms from a botanical gardens, assuming they were
the consumable variety. The couple’s aunt later passed away from eating
the toxic fungi.
Thankfully, scientists have developed a treatment for death cap
poisoning that shows great promise, but it is not yet widely available.
The Suicide Tree (Cerbera odollam)
India
India
The state of Kerala, on the southern tip of India, is know for many things. Bull Surfing, fisheries, rice paddies, tea farms, and a suicide rate well above the national average.
The Suicide Tree (photograph by Agnes Rinehart)
One of the reasons cited for that last bit of grim notoriety is the
plentiful abundance of Cerbera odollam, know colloquially as the Suicide
Tree, which grows in salt marshes and other swampy areas. Tea or food
made from the Suicide Tree has been the go-to method for those wanting
to take their own life for generations, and more recently the tree has
been suspected as a “perfect” murder weapon in a slew of suspicious
deaths.
Since the toxic glycosides in the tree leave nary a trace and mix
well with food, it’s convenient for suicides who want to avoid shame and
murderers who don’t want to tip off authorities. While some people are
content to blame the tree, recent social programs have sought to lower
the deaths by Suicide Tree in Kerala by addressing the underlying sociological causes, and not by blaming commonplace vegetation.
Snake Root (Ageratina altissima)
North America
North America
Snake Root is a tiny flower native to North America. It contains the
toxin tremetol and was responsible for thousands of deaths during the
1700s and 1800s.
Snake Root (1913 illustration) (via USDA PLANTS Database)
photograph by Bob Heitzman
European settlers, unlike the native population, were unfamiliar with
the pleasant-looking flowering weed and did not recognize the danger it
posed to their livestock and themselves. When eaten by a cow, the plant
renders her milk and meat poisonous. Those unfortunate enough to
consume a poisonous cow product, most notably Nancy Hanks Lincoln, would
become violently ill with vomiting and trembling. The future president
was only nine years old when his mother succumbed to the poison, one of
several people in the town of Pigeon Creek, Indiana to contract what was
known as "milk sickness."
It took many decades for scientists to connect milk sickness to snake
root, but now the plant is kept far away from grazing livestock. Today,
it grows in forests in the south and central United States, especially
along streams, and is sometimes mistaken for ordinary nettles.
Water Hemlock
North America
North America
Water Hemlock (via Wikimedia)
Like its European cousin Poison Hemlock, Water Hemlock bears an
unfortunate resemblance to edibles like cilantro and carrots, and grows
in wetlands all over North America, especially in Western States where
it continues to be a threat to livestock.
Scores of people have died over the years, including when in 1992 a young man in Maine mistook it for wild ginseng. It's even thought that a person can suffer mild symptoms just by handling the plant and there are claims that people have been poisoned by using the hollow stems as straws.
Oleander (Nerium oleander)
Gardens Across the United States and Europe
Gardens Across the United States and Europe
Oleander (via Library of Congress)
It seems at the very least unwise, but two of the deadliest plants to
humans are ubiquitous in ornamental gardens all across the world,
especially in the United States and Europe.
So widespread is the cultivating of oleander in warm climates that
botanists are unsure of its regional origins. Popular for its vibrant
colors, oleander is a hearty, decorative shrub commonly planted in
public spaces and private backyards and gardens, despite containing the
deadly toxins known as glycosides. It is even the official flower of Galveston, Texas, which holds an Oleander Festival annually, and has an oleander park where the plant grows.
Oleander illustrated by Lena Lowis (1878) (via Wikimedia)
The fear of oleander is so endemic in American culture that one of the most persistent urban myths listed on snopes.com
tells the story of a troop of unlucky boy scouts (sometimes girl
scouts) that uses oleander sticks to toast marshmallows and dies as a
result. The incident never happened, and it is highly unlikely
marshmallows toasted on oleander sticks would be fatal. However, people
should still fear the plant.
Ingesting just a few of its leaves would kill a human, as visitors to the Myrtles Plantation in
Louisiana find out, since oleander poisoning features in the estate's
ghostly history. Legend has it that a servant looking to ingratiate
herself with the family baked some oleander leaves into a cake, thinking
this would be a holistic cure for some ill children. The children and
their mother died, the servant was hanged, and ghostly apparitions
ensued.
Castor Bean Plant (Ricinus communis)North America and Europe
1887 illustration of castor bean by Franz Eugen Köhler (via Wikimedia)
The other deadly garden resident is the castor bean. Although castor
oil, derived from the castor beans, is used both for medicinal purposes
and as an industrial lubricant, the plant contains ricin, a toxin so
deadly to human’s that castor bean plants are consistently ranked at the
top of the world’s most deadly plants. Fans of the American television
show Breaking Bad will recognize it as the plant from Walt’s
garden from which he made ricin to poison his enemies (or in one case,
the child of his enemy’s girlfriend).
Making castor bean plants even more spooky is that fact they come in
enough various forms, owing to breeding for different purposes, that it
can be tricky to recognize them. They are native to the Mediterranean
and grow as an ornamental tree in countries like Greece, while in more
temperate climates in the United States are grown as an annual.
Africa
Ratbane (Dichapetalum cymosum and D. Toxicarium)
Ratbane (Dichapetalum cymosum and D. Toxicarium)
Ratbane (via eol.org)
For thousands of years, Ratbane caused very little trouble in its
native West Africa. Local fauna coexisted with the plants for thousands
of years, likely developing an immunity. Local people knew not to eat
it. But with the arrival of Europeans and their livestock, the plant
quickly became a threat to grazing animals, killing them in large
numbers.
It also caught the attention of the pest control industry as a
potential poison for rats and other mammals, including coyotes. The
plant contains powerful poison sodium fluooacetate, which was extracted
and widely used to kill unwanted mammals, including being placed into
livestock collars designed to kill attacking coyotes that bit the animal
on the neck. Ratbane was banned for commercial use in the United States
in 1972, but the plants still grows wild and plentiful across Africa
and livestock farmers have learned to manage it so as not to expose
their herds.
The West Indies
Jequirity Beans (Abrus precatorius)
Jequirity Beans (Abrus precatorius)
(via USGS Plants of Hawaii)
Handcrafted jewelry and musical instruments from the West Indies are
often made with ladybug-like beans from a plant known as the Rosary Pea
or as Jequirity Bean. These “all natural” beads contain the deadly
poison abrin, which is similar to ricin. So potent is the poison that it
is thought that if a jeweler punctures the beads while stringing them,
exposure to the poison could be fatal. More well-documented are the
cases of jewelry owners ingesting a bead and dying. Although the outer
shell is so hard that if it’s not chewed or punctured, the beans can
pass through the body harmlessly. The operative word being if.
Despite the risk, products made with the beads are widely available and
make their way into stores. In 2011, a number of British retailers
recalled thousands of bracelets that were for sale in gift stores across
the UK after a botanist who worked at a horticulture attraction
alerted authorities. The plant is probably native to Indonesia, but
grows copiously and invasively in tropical climates and jungles around
the world including in as far flung places as Trinidad & Tobago, India, Hawaii, and the southern United States.
Toxic Blue-Green Algae (Cyanobacteria)
Everywhere
Everywhere
Scientists don’t know what causes a normally harmless population of
blue-green algae to suddenly go all serial killer and release toxins on a
large scale, but they do, and occurrences are getting more frequent.
These unpleasant events, known as a bloom or red tide, can happen
pretty much anywhere algae lives in the world (saltwater or fresh), and
if it happens in a place where humans or animals or fish are exposed,
deaths and sickness often follow. Although human fatalities do occur,
the major danger is to fish and other aquatic life, and the resulting
economic damage can be significant.
2010 Filamentous Cyanobacteria Bloom near Fiji (via NASA Earth Observatory)
Blue-green algae is also the oldest species on this list, with
fossilized remands indicating that they’ve been around and doing their
thing before the other life forms on this list existed. Scientists have
determined that they were essential in the evolution of plant life and
the developing of Earth’s life-encouraging atmosphere.
In fact, every deadly thing on this list plays an important part in
the ecosystem that sustains all life on Earth. Some even provide
life-saving medicine or extremely helpful industrial products. Most of
them are beautiful, and all of them should, like nature itself, be
respected.via