< Previous | Contents | Next >
Insectivorous plants of India
1. Drosera or Sundew inhabiting wet infertile soils or marshy places
♤ Insect trapping mechanism: The tentacles on the leaves secrete a sticky fluid that shines in the sun like dewdrops. Therefore the Drosera. are commonly known as ‘sundews’. When an insect lured by these glistening drops alights on the leaf surface it gets stuck in this fluid and are absorbed and digested.
2. Aldrovanda is a freefloating, rootless aquatic plant, the only species found in India, occurs in the salt marshes of Sunderbans, south of Calcutta. It also grows in fresh water bodies like ponds, tanks and lakes.
♤ Insect trapping mechanism: On the leaf midrib are found some sensitive trigger hairs. The two halves of the leaf blade of Aldrovanda close along the midrib the moment an insect comes into contact with the leaf, trapping the victim inside.
3. Nepenthes: The members of the family are commonly known as ‘pitcher plants’ because their leaves bear jar-like structures.
♤ Distribution - It is confined to the high rainfall hills and plateaus of north-eastern region, at altitudes ranging from 100 - 1500 m, particularly in Garo, Khasi and Jaintia hills of Meghalaya.
♤ Insect trapping mechanism: Nepenthes conforms to the pitfall type of trap. A honey like substance is secreted from glands at the entrance of the pitcher. Once the insect enters into the pitcher, it falls down because of the slipperiness.
♤ The inner wall, towards its lower half, bears numerous glands, which secrete a proteolytic enzyme. This enzyme digests the body of the trapped insects and nutrients are absorbed.
4. Utricularia or Bladderworts: The Bladderworts generally inhabit freshwater wetlands and waterlogged areas. Some species are associated with moist moss covered rock surfaces, and damp soils during rains.
♤ Insect trapping: Utricularia in its bladders mouth, has sensitive bristles or hairs. When an insect happens to contact these hairs the door opens, carrying the insect into the bladder along with a little current of water. The door is shut when water fills the bladder, The enzymes produced by the inner wall of the bladder digest the insect.
5. Pinguicula or Butterwort: It grows in the alpine heights of Himalayas, from Kashmir to Sikkim, along stream-sides in cool boggy places.
♤ Insect trapping mechanism: In Pinguicula, an entire leaf works as trap. When an insect lands on the leaf surface, it gets stuck in the sticky exudate.the leaf margins roll up thus trapping the victim.