Spooky Plants for Halloween

Halloween is just around the corner, which provides a good excuse to explore the world of weird and scary plants. These particular plants often exist in harsh environments or require specific pollinators. They rely on their strange attributes for survival.

Carnivorous plants are perhaps the most gruesomely fascinating to people, if the fact that there are more than 30 carnivorous plant societies around the world is anything to go by. Carnivorous plants "eat" insects. Carnivorous plants more actively involved in the kill have the most fascinating characteristics. For example, the hinged leaves of the Venus flytrap (Dionaea muscipula) snap closed in less than a second after an insect brushes against hairs on them. The hair movement triggers chemical-electrical signals that cause one surface of the leaf to grow rapidly, quickly changing the curvature of the leaves so that they slam together to trap the insect inside.

Another group of active killers are several species of bladderwort, which are mostly found in water or waterlogged areas. Given their name, it’s not suprising to learn that thy have a bladder or vessel as part of their makeup. The plants can pump out the water from their bladders, creating a low-pressure area inside. Lunch, in the form of an aquatic organism, arrives at the door of the bladder, triggering it to open (scientists are not sure how) and the water rushes in, bringing the prey along with it. The door closes and digestive juices released in the bladder finish off the job.

While carnivorous plants generate the most attention in the weird-plant universe, second place probably goes to super-stinky plants. Just as your dog may be attracted by the odor of rotting things found during your daily walk, so too are certain pollinators attracted to plants whose perfumes are offensive to humans.The corpse flower (Amorphophallus titanum) is perhaps the most (in) famous stinky plant. Its enormous (six to eight feet) inflorescence is astounding in its own right, but its smell is apparently quite sickening. The plant produces these single flowers rarely, and the prospect of a bloom is grounds for greenhouses and conservatories to send out news releases so that the curious—and gas mask wearing—can experience it.

The milkweed family (Asclepiadaceae) also features some smelly cousins. One is the Stapelia gigantea, whose common names—carrion flower, dead horse plant—hints at its odoriferous nature. Other flowers that have a particular eau-de-rotting-flesh scent include the three-foot-tall dragon arum (Dranunculus vulgaris), which looks like a maroon calla lily on steroids and the similar but smaller voodoo lily (Sauromatum venosum). Oddly enough, you can find these three plants for sale through specialty nurseries.

Parasitic plants, which rely on another plant for nutrients or water, can also be kind of creepy because they grow on or inside their hosts. One notable parasitic plant, the Rafflesia arnoldii, is also a member of the stinky-plant society and produces the world's largest flower to boot. It lives as a network of cells inside its host, a vine from the grape family. It blooms every once in a while by forming a lump that emerges from the bark of the vine and opens into a massive flower up to three feet in diameter. The flower's "perfume" attracts pollinators such as carrion beetles.

So why not ditch the Halloween pumpkin this year and instead decorate the front porch with a collection of Venus flytraps, sundews and pitcher plants featuring insects in various stages of entrapment and digestion? Or, if you are a misanthrope, consider stocking up on stinky plants—one or two outside the house should do the job of repelling the neighborhood trick-or-treaters.