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In certain forests, when you look up you will see a network of cracks formed by gaps between
the outermost edges of tree branches. It looks like a precisely engineered jigsaw puzzle, each
branch growing just perfectly so it almost, _(11)_, touches the neighboring tree. This beautiful
phenomenon is called crown shyness.
Scientists have been discussing crown shyness since the 1920s, proposing (12)_explanations
for the phenomenon. Some researchers point out that as trees often grow close together, treetops
can easily collide and break when swayed by the wind. In order to protect their branches from
breakage, trees maintain "shyness gaps"-spaces large enough to prevent them from touching
Tot
their neighbors.
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2201 (A
qelp.
Other scientists suggest that plants, like animals, _(13)_ resources-nutrients, water, space,
and light. In forested areas with thick tree crowns, there is intense struggle for these resources.
Gaps in the treetops resulting from crown shyness may allow trees to increase their (14)_ light
and enhance photosynthesis. Additionally, by having branches that do not touch those of their
s, trees
may be able to limit the spread of leaf-eating insects, and potentially also the
s, and
transmission of diseases from tree to tree. _(15) decades of investigation, there is no consensus
on exactly what causes the beautiful and mysterious phenomenon of crown shyness.
(A)
CD 11. (A) in no time
(B) by all means
(C) but not quite(D) and pretty much
