The willow and other similar trees, which have their boughs lopped
every 3 or 4 years, put forth very straight branches, and their
shadow is about the middle where these boughs spring; and towards
the extreme ends they cast but little shade from having small leaves
and few and slender branches. Hence the boughs which rise towards
the sky will have but little shade and little relief; and the
branches which are at an angle from the horizon, downwards, spring
from the dark part of the shadow and grow thinner by degrees up to
their ends, and these will be in strong relief, being in gradations
of light against a background of shadow.

That tree will have the least shadow which has the fewest branches
and few leaves.