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Ask a Master Gardener: The Strange World of Carnivorous Plants

By Jennifer McDonald, Mobile County Master Gardener www.mobilecountymastergardeners.org


It is a foggy dawn in a murky bog, and an unseen frog’s eerie croak cuts through the silent stillness. The sun is still low to the east as a newly-awakened hawk soars overhead, wings outstretched, in a ruthless mission to locate its next meal. From somewhere within the weeds, a large gator emits a low growl and slaps the shallow water with its fearsome tail, startling a nearby cottonmouth who shows his gaping white mouth in protest.


As the sun continues to emerge from the horizon, the small community of predators and prey go about their daily dance. Amongst the landscape of peaceful and diverse vegetation, a different type of killer lies in wait. A pretty yellow butterfly never sees it coming as she cheerfully approaches the colorful tubular plant with the strangely alluring scent. After only the briefest taste of the plant’s sweet nectar, the butterfly finds itself sinking down into its hungry trap, where escape is futile.


Carnivorous plants, who survive by trapping and consuming insects and other animals, have long been a source of creepy fascination to humans. My first encounter with them was in the popular ‘80s movie “Little Shop of Horrors,” featuring a massive talking carnivorous plant that feeds on human blood. To this day, it’s hard for me to see a Venus flytrap without singing, “Feed me, Seymour,” the plant’s plea to its owner to obtain victims for its sustenance.


Carnivorous plants are native to all continents except Antarctica and parts of the Pacific Islands. There are hundreds of species that share the primary traits common to carnivorous plants: They use traps to capture prey; they kill and digest the prey; and they grow and develop using the nutrients absorbed from their prey. Carnivorous plants still generate their energy from photosynthesis, like other plants, but they have adapted to live in places where the soil has limited nutrients, especially nitrogen.


Though they share these common traits, carnivorous plants are a diverse group of unique species. Some are rooted in soil and others are rootless and free-floating. They come in a variety of different shapes and sizes and use a variety of mechanisms for trapping their prey.


There are five basic trapping mechanisms. Pitfall traps, which are found in pitcher plants, are formed by rolled leaves filled with digestive enzymes that dissolve prey that fall inside. Pitfall traps are a type of passive trap, which means they attract prey without moving. Pitfall traps attract insects and other prey using bright colors and scented secretions. Their rolled leaves are slippery on the inside, which causes the insects to slip and fall in.


One of the best places to see pitcher plants in our area is the Weeks Bay Pitcher Plant Bog at the Weeks Bay Visitor Center in Fairhope. The pitcher plants, which begin to blossom in the early spring, can be observed from a boardwalk.


Another type of passive traps are lobster-pot traps, which use inward-pointing hair to force and keep prey inside. This type of trap is used by certain species of pitcher plants which also use scented nectar to lure insects inside where they can’t escape.


Flypaper traps, found in plants such as butterworts, use a sticky substance to trap their prey. Insects are drawn by the sweet scent of the mucus the plants produce. Once the insect lands on the plant, they are unable to free themselves and are digested by the enzymes and acids secreted by the plant. Sundews use a creepier example of flypaper traps having sticky tentacles that extend from the plant, grabbing prey that come too close and smothering them in mucus.


Plants that utilize active traps also use some form of movement to catch their prey. Bladder traps suck prey in using an internal vacuum. Bladderworts make up the largest group of carnivorous plants, and they are some of the most highly developed plants in existence. These aquatic plants have small bladders that act like a trap door, activated when the prey touches the hairs around the door. When triggered, water rushes inside, sucking the animal into the bladder.


You can find bladderworts in certain parts of the Mobile Tensaw Delta. Beneath the yellow flowers that emerge from the water you’ll find a frilly mass that extends beneath the water. The mass is covered in black specks, which act as mouths that consume prey using an internal vacuum system.


Finally, snap traps are used by the most famous carnivorous plant of all: the Venus flytrap. These plants, which grow naturally primarily in North Carolina, contain leaves that quickly snap shut like jaws. The teeth on the edges of their leaves contribute significantly to their creepy appearance, making them the quintessential carnivorous plant. Fortunately, most do not consume human blood, at least as far as we know.


Unfortunately, approximately a quarter of carnivorous plant species are at risk of extinction due to factors such as land development, climate change, and illegal poaching. Arguably the most fascinating, carnivorous plants include some of the strangest and perhaps creepiest of plants, which are well worth studying and protecting.

Venus Flytrap


Pitcher Plant

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