They Kill to Survive : Carnivorous Plants

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Posted By : ScienceIndia Administrator

Carnivorous plants grow in locations where the soil is too poor in minerals and/or too acidic for most plants to survive. Rather than relying on photosynthetic glucose to survive, these plants supplement available nutrients and minerals (which plants normally obtain through their roots) with the constituents of their insect prey.

1. Pitcher Plant (Nepenthes Distillatoria) :

Pitcher plants have modified leaves known as pitfall traps, a prey-trapping mechanism featuring a deep cavity filled with digestive fluid liquid. The rim of the pitcher is slippery, moistened by condensation or nectar, causing insects to fall into the trap. Pitcher plants may also contain waxy scales, protruding aldehyde crystals, cuticular folds, inward and downward pointing hairs on the inside of the pitcher to ensure that insects cannot climb out. The small bodies of liquid contained within the pitcher traps are called phytotelmata. They drown the insect, and the body of it is gradually dissolved. This may occur by bacterial action or by enzymes secreted by the plant itself. Furthermore, some pitcher plants contain mutualistic insect larvae, which feed on trapped prey, and whose excreta the plant absorbs. Whatever the mechanism of digestion, the prey items are converted into a solution of amino acids, peptides, phosphates, ammonium and urea, from which the plant obtains its mineral nutrition.

2. Venus Flytrap (Dionaea Muscipula) :

It catches its prey, chiefly insects and arachnids with a trapping structure formed by the terminal portion of each of the plant’s leaves, which is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap closes if a different hair is contacted within twenty seconds of the first strike. The requirement of redundant triggering in this mechanism serves as a safeguard against wasting energy by trapping objects with no nutritional value. The mechanism is so highly specialized that it can distinguish between living prey and non-prey stimuli. It is found in Carolina, US.

3. Cape Sundew (Drosera Capensis) :

Cape sundew produces strap-like leaves, up to 3.5cms long and 0.5cms wide, which are covered in brightly coloured tentacles which secrete a sticky mucilage that traps arthropods. When insects are first trapped, the leaves roll lengthwise toward the center. This aids digestion by bringing more digestive glands in contact with the prey. This movement is surprisingly fast, with completion in thirty minutes. All species of sundew are able to move their tentacles in response to contact with edible prey. The tentacles are extremely sensitive and will bend toward the center at a rapid pace. According to Charles Darwin, the contact of the legs of a small gnat with a single tentacle is enough to induce this response. This response to touch is known as thigmonasty. The plant is native to Cape in South Africa.

Courtesy : Science India Magazine 

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