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Lianes
Not all plants which
thrust their way into the forest canopy are trees. Lianes, for example,
have their roots in the forest floor, but rely for their support upon
existing trees.
Often starting out
as shrubs,
the lianes
put out long branches which attach themselves to tree trunks and climb
up until they reach the sunlight, at which point they generate leaves
and frequently create large crowns.
Epiphytes
Like the lianes, epiphytes do not provide their own support, but in
contrast they are not rooted in the ground at all. Instead, they grow
on the surface of the canopy trees, rooting in crevices
where humus
has accumulated. These roots, however provide only an anchorage, and
the epiphytes do not draw their nutrients from the host tree. Exactly
where these plants do obtain their nutrients varies from one species
to another, some collecting falling plant matter, others receiving organic
matter from the insects which pollinate them. Common epiphytes are orchids,
bromeliads and ferns.
Stranglers
Found only in the
tropical rain forests, stranglers start out as epiphytes, but at a certain
point in their growth they produce roots
which wrap around the trunk of the tree on which they live, and descend
into the ground. This provides them with increased nutrients, allowing
them to grow towards the canopy. Eventually the strangler surrounds
its supporting tree with roots, which ultimately kills it. However,
the trunk of the tree remains, and continues to support the strangler.
Most stranglers are figs.
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