Tree and plant varieties serve a very important purpose in
ornamental horticulture. In unnatural urban
areas, where the environment can be unforgiving, plants are not always given
the opportunity to evolve. In U.S. cities like Philadelphia ,
Washington , D.C., and New York City the average life of a street
tree is an average of 7 years. In
harsher environments, like Chicago
with its lake effect winters, the average life span can be even less.
In Ecological restoration seed provenance is a key
principle. If you were installing a rain
garden in essence you would be mimicking a flood plain. Imagine a flood plain near a river. The river and the flood plain have been there
for thousands of years. Throughout fluvial
changes, human impact, diseases, pests, and weather fluctuation the flood plain
has existed and evolved as a plant community.
Some plants have died, but many have thrived because of there genetic
diversity. Now recreate that in your
yard…tomorrow.
I may have heard and collective audible gasp. Relax.
This is possible. It can be done
by planting plants grown for locally collected seed. Provenance is the origin and location of the
collected seed. The seed contains the
DNA of the plants in that region so they should react in the same way to
similar conditions; say within a 200 mile radius of where the seed was
collected. If you were to plant a variety, a clone propagated
from either tissue culture, budding or grafting, it may not have the same
chance to evolve. Clones are selected
mainly for specific characteristics.
These characteristics could be drought tolerance, heat tolerance, or a
specific flower color. A plant may have been cloned in a region or country where
a local plant disease does not exist.
When planted in mass in your rain garden it now does not have the tools
to evolve, adapt, or over come this disease.
Another example of this could be extreme weather conditions in a certain
region.
How so you know which plants to use? This is easy.
While planning your project visit a natural area that is similar in your
local area. When purchasing you plants ask
you local garden center or nursery what the provenance is for the plants you
are purchasing. Most nurseries keep
records of their seed collection sources.
Make sure you are buying straight species rather than varieties. For example, Acer rubrum (Red Maple) is straight species but Acer rubrum ‘Red Sunset’ (Red Sunset Red
Maple) is a variety that is commonly cloned by tissue culture for its brilliant
red fall display. These things will help
your ecological solution be successful.
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