Venus Flytrap: A Carnivorous Plant

The Venus flytrap is a carnivorous plant which mainly preys on small insects and arachnids. It is scientifically known as Dionaea muscipula. The trapping portion of the plant is formed by the terminal portion of the leaves which are lined by tiny hairs on their inner surfaces. When any insect of spider coming in contact with hairs on the leaves, touches them then the trapping structure closes within 20 seconds of the first strike. The common name of the plant has been derived from the Roman goddess of love and the generic name refers to Dione. Dionaea is a monotypic genus which is closely related to waterwheel plant and sundews.

Venus flytrap is a small plant whose structure can be described as a rosette of 3-7 leaves. The leaves arise from a subterranean stem which is actually a bulb like object. The stem attains a length of about 3-10 cm which is dependent upon the time of the year. Longer leaves are generally formed after flowering. The leaf is divided into two regions namely a heart shaped petiole and a pair of terminal lobes hinged at the midrib which finally form the trap. The upper surface of these lobes contains anthocyanins pigment and its edges secrete mucilage. The leaves exhibit rapid plant movements especially when stimulated by a prey. The trapping mechanism is initiated when the prey comes in contact with any of the three hair-like trichomes present on the upper surface of these lobes. The trapping mechanism is very potent and it can easily differentiate between a living and non-living prey as well as the falling raindrops. The edges are fringed with hair-like protrusions or cilia that prevent the prey from escaping.

The evolutionary history of this plant is unknown. The speed of closing of the trap largely depends upon a number of factors like amount of humidity, light, size of prey, and general growing conditions. These plants are not humidity dependent like other carnivorous plants for example Nepenthes, Cephalotus, most Heliamphora, and some Drosera. The plant exhibits variations in petiole shape and length. When grown from seeds the plant takes 4-5 years to attain maturity and can remain alive for 20-30 year if proper conditions for survival prevail. It is prey specific like other carnivorous plants. The prey is limited to spiders, beetles and other arthropods. The diet of this plant on a rough estimate includes 33% ants, 30% spiders, 10% beetles, and 10% grasshoppers, with fewer than 5% flying insects.

The mechanism of trapping is largely dependent upon elasticity, turgor and growth. In active state the lobes are convex but in closed state they are concave. When hairs are stimulated an action potential is generated that passes across the lobes and stimulates the cells in the lobes and the midrib. Digestion occurs by the enzymes secreted by the glands present in these lobes. The aqueous leaf extracts are shown to have quinones such as the naphthoquinone plumbagin. Plumbagin is known to induce apoptosis, associated with the regulation of Bcl-2 family of proteins. Digestion completes in about ten days and the prey is converted into a husk of chitin. After digestion the trap again reopens and is now ready for another attack.

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