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Tetrastigma: Lianas
A constant struggle is underway in the thick tropical forests: a struggle for
light. It’s very dark in the lowest levels of the forest. To force their way
into the upper regions, trees have to invest a lot of biomass in a thick, sturdy
trunk. Lianas have found a shortcut to reach the top of the forest: instead of
growing their own thick trunk, they borrow one, climbing up other trees. Saving
on biomass, they still need solid stems to counteract gravity. Imagine a
thunderstorm in these forests and the lianas within the canopy! Lianas can take
on beautiful shapes: spirals twisted like corkscrews, ribbons, zig-zag steps,
forming socalled monkey ladders, and many others.
Lianas have developed independently in many different families of plants. Climbing
passion flowers and species of Aristolochia have eye-catching blossoms, one
reason they’re found in almost every botanic garden. You’ll rarely catch sight of
these beautiful flowers in the wild, as they bloom in the forest canopy, many meters
above the ground.
Lianas aren’t true parasites, meaning they do not grow into the tissues of the
supporting trees. However, they damage their “host” trees indirectly by reducing
the amount of sunlight they receive and by the extra weight they place on the host,
which can be immense, especially when it has rained and the plants are wet.
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Tetrastigma: Lianas (MP3, 631 KB)
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