4
Bluebell
pleasing to human eyes which
have been acclimated to current
standards of horticultural beauty,
but little remains of value for
wildlife.
Hardiness
Despite the overly-adaptable
nature of certain exotic species,
many introduced plants are
temperamental and require a lot
of work on the part of the
gardener if they are to thrive.
This may include frequent
fertilizing and spraying with
pesticides, both of which are
expensive and have a negative
effect on the environment.
In times of drought, these
plants will require additional
watering to survive, thus using
up large quantities of that
valuable resource when we most
need to conserve it. Plants
native to a given area, on the
other hand, have adapted
strategies over many years to
survive climate extremes in their
natural habitat.
Those species which grow in
arid regions have developed
smaller leaves, or even no leaves
at all, in order to lessen both the
need for water and its loss
through evaporation.
Prairie species “cooperate" by
distributing their roots at
various levels underground,
rather than having them all
concentrate on the nutrients
and moisture at a single level.
Although periods of major
drought may occur only once or
twice in our own lifetimes, even
species from normally wet
regions will have seen many
droughts during their evolution
and will be somewhat adapted.
Flowers may be shorter due to
lack of rain, but they will
generally bloom. Trees that are
severely stressed by drought will
actually produce more fruit
(seed) than usual, ensuring that
even if the individual tree dies,
the species will continue.
Native plants also frequently
have a resistance to common
fungal infections and insect
problems. Even if they are
attacked, they have developed
the skills to survive. Milkweed
plants are likely to be eaten by
caterpillars, yet their roots
persist and they return each
year.
Oak trees which are attacked
by insects will not only survive,
but the next year will produce
higher amounts of toxic tannic
acid, thus “fighting back" during
the new season of growth.
Some natives have other
distinct advantages over their
cultivated counterparts. A
number of landscape trees, such
as the Bradford Pear, have been
bred to provide a mass of showy
flowers in the spring, but that’s
the end of their performance.
A native Sourwood
(Oxydendrum arboreum), by
comparison, has beautiful white
blossoms in late spring, vibrant
fall foliage, and fruits which
persist through the winter.
The Bradford Pear is also an
example of what can happen
when we tamper with Mother
Nature. It has been used widely
for landscaping because of its
uniform, vase-like shape. This is
the result of breeding to get all
of the major limbs to emerge
from the same spot on the
trunk.
“When a soil loses fertility we pour on fertilizer,
or at best alter its tame flora and fauna, without
considering the fact that its wild flora and fauna,
which built the soil to begin with, may likewise be
important to its maintenance. It was recently
discovered, for example, that good tobacco crops
depend, for some unknown reason, on the
preconditioning of the soil by wild ragweed. It
does not occur to us that such unexpected chains of
dependency may have wide prevalence in nature."
– A Sand County Almanac
Aldo Leopold (1949)
