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Carnivorous Plants: Why Do They Exist?

Nicolette Goff is a watercolourist, writer, and dedicated gardener. She is always on the lookout for new and unique plants.

Being a gardener doesn't have to be dull. If you want something unique, carnivorous plants are bound to get attention. From the common Venus Flytrap to the Cobra plant, these unusual plants have fascinated nature lovers.

Because they have originated in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic bogs and rock outcroppings, they have adapted to garnering minerals and nutrients in bizarre ways. They all attract and trap prey, generally insects and arachnids, and produce digestive enzymes to digest and absorb the resulting available nutrients.

There are five unique subsets of carnivorous plants, according to their trapping mechanisms:

Pitcher Plants


Pitcher Plants - The Pitfall Traps

The first type of carnivorous plant utilizes pitfall traps, and the most common is the pitcher plant. These traps require prey tumbling into the plant and being unable to escape. The pitchers or traps attract insects by visual lures or by nectar. The traps or pitchers are formed in different ways, depending on the genus.

One type, the Old World Nepenthe, have a pitcher that is attached to the end of a tendril which depends from the underside of a leaf. The New World Sarraceniaceae family consists of ground-dwelling plants whose pitchers arise from a horizontal rhizome. In this family, the entire leaf forms the pitcher. Heliamphora, or marsh pitchers have a simple rolled-leaf pitcher, at the tip of which is a spoon-like structure that secretes nectar to attract unwary insects.

These plants undergo constant evolution, as liquid can gather in the pitchers of the plant in addition to the bugs that the plant eats. Some of these have developed an 'overflow', similar to that in a bathroom sink. Excess water can flow out so the digestive enzymes are not diluted.

These plants range from beautiful to bland, and do not have moving parts like their snap trap cousins. Over 40 types of pitcher plants are found worldwide.

Venus Flytrap


Venus Flytrap - The Snap Trap

The most well known type of carnivorous plants is the snap trap family. Snap traps rely on a mouth that snaps around its prey, and the plant will eat anything it snares. The traps are leaves whose terminal section is divided into two lobes, hinged along the midrib.

The trapping mechanism is tripped when prey items stumble against one of the hair-like trichomes that are found on the upper surface of each of the lobes. The trapping mechanism is so specialized that it can distinguish between living prey and non-prey stimuli such as falling raindrops.

When two trigger hairs are touched in succession or one hair touched twice the lobes of the trap will snap shut in about a tenth of a second! When trigger hairs are touched, the trap snaps closed, trapping the insect. The stiff hairs at the leaf edges mesh together, preventing the insect from escaping, and digestion occurs over the next two or three weeks.

Sticky Traps


Flypaper Traps - the Sundew

Flypaper traps are among some of the most interesting and widespread carnivorous plants, with over 170 species.These plants secrete a glue or mucilage from glands which ensnares and breaks down insects for food. Some, like the sundew, have these mucilage glands on the tips of long tentacles which aid in the trapping process.

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A second group of glands secretes esterase, peroxidase, phosphatase and protease enzymes which both both dissolve the insect and free the contained nutrients. The nutrient soup is then absorbed through the leaf surface and fuels the plant's growth. 

These carnivorous plants should be treated with caution in the home, as the secretions can cause rashes or inflammation of the skin. 

Bladder Traps

Pond bladderwort

Pond bladderwort



Bladder traps, exclusive to the bladderworts, are a fascinating subset of carnivorous plants. Bladderworts are unique in that the underwater leaves bear small oval "bladders" that trap and digest small aquatic creatures. Bladderworts are usually found in quiet shallow, acidic waters and can form dense mats.

These plants function through the osmosis of water to create a suction within the bladder of the plant. Once an insect or aquatic species has been trapped within, escape is difficult. Unlike many carnivorous plants, these are more commonly found underwater than above ground, and some lack roots.

Above ground species of bladderworts (horned bladderworts or Utricularia cornuta) grow in wet and marshy soils, the leaves hidden in the mud. The flowers rise from a single bare stock.



The Corkscrew Plant: Genlisea

Last but not least are the lobster pot trap plants. There are approximately 21 species of the Genlisea genus, commonly known as corkscrew plants.

These plants function by giving their prey a simple way to gain entry, but slim chance of escape, similar to a lobster or crab trap. They generally grow in a semi-aquatic area, and if you dig up the innocuous-appearing plant, they have a network of roots. Except they aren't true roots but deadly traps.

In the case of the corkscrew plant, the traps are underground -- the insides of the plant's roots have downward pointing obstructions or hairs so the prey, tiny soil-borne invertebrates, cannot move backward.

Carnivorous Plant vs Insect

Many of these plants are rare in their natural state, and should not be collected from the wild. If you are interested in growing them, they should be purchased from a reputable grower who uses tissue culture or vegetative means to grow the plant, or who starts them from seeds.

Carnivorous plants should be placed out of the reach of young children and pets. While most of them are mostly non toxic to humans, eating one of these plants could be harmful, due to the digestive enzymes that the plant uses to devour prey.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2008 Nicolette Goff

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