Gardening Tips from Science Fiction and Fantasy: Plants and Fungi to Avoid

May 2, 2023 | Isabel

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It’s always exciting to discover a new plant, flower or fungus. And the desire to bring it home and add it to your garden is understandable. However, there's one thing we've learned reading science fiction: it's a bad idea. Always take caution when transplanting a newly discovered species, especially one from another planet. Better yet, just don't do it. It’s far too likely that it will become an invasive species and harm Earth’s natural ecosystem.

According to the Invasive Species Centre, invasive species are "plants, animals, insects, and pathogens that are introduced to an area and cause harm to the environment, economy, or society." In short, a non-native species — even if it's from another planet — is only considered invasive if it causes harm. If you can’t be sure if your interdimensional or unearthly plant is invasive, consult an expert.

Read on for some of the popular plants and fungi that are invasive to Earth and should be eradicated at all cost. This guide was created by the staff of the Merril Collection of Science Fiction, Speculation and Fantasy. We’ve included tips on how to deal with these organisms, too.

Unearthly Garden exhibit introductory case

More species have been catalogued by Merril Collection staff than are mentioned here. Visit the The Unearthly Garden: An Exhibit of Fictional Flora and Fungi to discover them all. The exhibit runs until June 30, 2023, and can be viewed during regular Merril Collection hours (weekdays 10-6, Saturdays 9-5).

Our expert staff will also be holding a related talk on May 10, 2023, at 6:30pm. Feel free to come and ask your questions about alien plants in person.

One of the most dangerous invasive species ever known is the body snatchers. These plantlike aliens drift across space until they find a hospitable planet with hosts in which they can replicate. They replace their hosts with identical copies, leaving the original bodies to disintegrate. Body snatchers strip entire planets bare, turning them into dead worlds.

Body snatchers decimated the town of Mill Valley, California, in the 1950s. Luckily, they were met with fierce resistance from residents and decided to flee rather than fight. Jack Finney documented this incident in his 1954 book The Body Snatchers. There have also been several instructive films about the body snatchers made over the years. The Merril Collection will be screening one on June 9, 2023 for your further edification.

How can you tell if a body snatcher has replaced a host? The lack of emotion. It's the only thing they can't replicate. In their original form, body snatchers are three-foot-long seed pods. If discovered in your garden or community, destroy pods and duplicates with fire immediately.

Triffids were not viewed as invasive when they were first cultivated, though they have always been dangerous. Triffids are easy to spot. They range from seven to ten feet in height, with a root mass at the base and a long, neck-like trunk ending in a funnel-shaped flower. Three appendages on their root ball enable them to walk. They are carnivorous and their venomous stingers can kill a fully-grown human. They also produce a valuable, nutritious oil.

Triffids can be successfully farmed. However, if not kept tightly under control they will spread and prey on humans. John Wyndham's 1951 book, The Day of the Triffids, documents a meteor shower that blinded most of the human race. In the ensuing collapse of civilization, triffids quickly took over the world.

The fastest a triffid can move is at a walking pace. Therefore, the best way to survive is to flee.  Decapitating them will make them less of a threat, but will not kill them. For that, it is best to use fire. Amateur gardeners should not attempt to cultivate triffids.

Shriekgrass is dangerous both to the land and the people around it. As described by Rachel A. Rosen in her book Cascade, shriekgrass is "pale and spindly, sharp fronds edging its drooping stems. It sways in the wind like the legs of a centipede or a human spine." When cut, blades of shriekgrass will cry out in pain, hence its name.

Shriekgrass grows where magic has touched. There is no known way to eradicate it. Proximity to shriekgrass appears to turn humans into demons, for which there is no cure. Avoid at all costs. If shriekgrass has invaded your garden, you will need to move house.

"...mushrooms are not the only fungus. There are many, many types in the world. We walk constantly in a cloud of their spores, breathing them in. They inhabit the air, the water, the earth, even our very bodies." – Mrs. Potter, What Moves the Dead

The tarn fungus is a rare, aquatic fungus that originated in a lake on the grounds of Usher, England. It grew there for centuries and eventually spread to the brains and bodies of fish and hares using its hyphae – thin filaments resembling white hairs. Infected animals show no fear and move strangely. This behaviour in local wildlife is the first clue of a tarn fungal invasion. The animals can only be killed with fire. Even dismemberment is ineffective.

Should you suspect that your garden pond has become a breeding ground for the tarn, drain the water immediately. The tarn is best handled by professionals. It can be killed using strong alcohol, fire or sulfur. If you insist on trying to treat it yourself, be sure you wear protective gloves, masks and outer garments.

The Beauty originated as a plague of yellow fungus that grew on human women. It has since changed form. The current variant was discovered growing on grave sites or places where dead bodies decomposed. Small, early mushrooms have an appetizing, beefy smell but are bitterly inedible. Eventually they will grow to the size and shape of a human woman, and develop mobility and sentience. These humanoid fungal creatures are capable of displacing humans at the top of the food chain. If you discover Beauty mushrooms in your garden, uproot the fruiting bodies and burn them. You will also need to hire a professional to excavate the site and remove any human remains.

A parasitic strain of the Cordyceps fungus was discovered growing on crops in South America. By the time it was found, contaminated food had already been sold around the world. When ingested, the fungus infects the human brain and takes over. Those who are infected eventually lose their higher brain function and will attack the uninfected.

The fungus’ spores are transmitted through the air to other plants. Should it be discovered in your vegetable patch, there is only one solution: burn it to the ground. Be sure to wear a hazmat suit to avoid inhaling any of the spores.

In summary, always wear personal protective equipment when dealing with otherworldly plants and fungi. And keep a source of fire at hand.

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This post was co-written with Ames G. Further thanks to Maya, Brian and Kim.