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Plants on other plants
Epiphytes grow on other plants which act as their support.
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They should not be confused with parasitic plants which feed off the host plant.
Epiphytes are classified as strict epiphytes and hemi-epiphytes.
The first group have no contact with the ground and survive on rainwater, the humidity in the air and mineral substances accumulating on the surface of the support plant. They are frequently horn-shaped, which channels the humidity and plant debris |
falling from the canopy (Bromelia, Platyceria and Orchids).
The second type germinates at the treetops, then sends long roots down to the ground (Ficus, Clusia, large philodendrons).
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Half angel, half devil!
Orchids have become expert in the art of deluding animals to ensure their own reproduction.
The orchid attracts the insect by smell, lure, or mimicry by taking on the appearance of the female insect.
The insect finds itself trapped inside the flower (a trap that closes, having to leave via a tunnel, sliding in a liquid), which prevents it leaving.
The insect carries pollen sacks known as pollinium attached to its body, which will later be deposited on the sticky stigma of the next flower.
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Grown for its pods, vanilla is the only edible orchid. Angraecum fragans from Mauritius is used in infusions, frequently being added to tea.
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The plants' revenge
Carnivorous plants gain an additional food supply from trapping insects.
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Nepenthus and Sarracenia have simple, urn-like traps into which the insect falls, where it drowns and is digested by bacteria.
Drosera and Pinguicula adopt the fly-paper approach: the attracted insect sticks to the surface of the leaves, cannot get free and becomes more firmly stuck.
Utricularia leaves produce tiny inflatable bags.
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Compressed and empty when resting, these pockets fill with air or water, sucking in the prey that brushes against them. This is the quickest of all known traps: 10 to 15 milliseconds is all it takes.
The Venus Fly Trap's jaw is the most spectacular trap. The attracted insect settles on the leaf which closes around it. Excrement from the prey triggers a chemical stimulus which causes it to be digested.
The evolution of carnivorous plants is not always an advantage for the excess of bodies can cause the plant to rot.
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