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What are native
plants?
Native plants occur
naturally in a region. For example, Douglas-fir is a native
plant in much of Western Washington. English holly, on the other
hand, is not a native plant in Washington state because it was
originally brought here by humans from England.
Non-native plants are often called
"exotic plants" or "introduced plants". Occasionally they can become a problem,
spreading aggressively and damaging precious wildlife habitat. The damage is
sometimes permanent because the plant is impossible to completely remove, and/or
the plant emits soil chemicals that keep natives from re-growing
Why use native plants?
The plants native to a region have
grown alongside native insects, fungi, plant diseases, wildlife, and other
native plants for thousands of years. This long-time association has produced a
complex web of inter-relationships, by which the native plant may depend upon
numerous other native organisms to survive and flourish, one or many native
organisms may, in turn, depend upon that native plant to survive.
In the process, native plants have
evolved the ability to attract native animals that benefit them (such as
pollinating and seed-dispersing insects and birds), and to repel or survive
native organisms that harm them (such as plant viruses and chewing insects).
As a result, native plants often
attract a wider variety of native animals than do exotic plants. In addition,
the plants native to an area are adapted to growing in that region's soils and
climate, and so generally require less maintenance (such as watering and
fertilizing) than non-natives.
When is a plant not native?
Using native plants raises important
issues about exactly what "native" means. For example, Red-osier Dogwood (Cornus
sericea), is native to Western Washington. However, it is also native to a
number of other places, including Alaska, southern California, Michigan, and
Maine! Although they are all the same species, red-osier dogwoods growing
naturally in other areas have adapted to a very different combination of
climate, soil, diseases, and other plants and animals from what is found in
Western Washington. As a result, you could say that dogwoods native to Michigan
are about as "native" to Western Washington as palm trees!
Ideally, you want to use plants
similar to those that occur naturally nearby. Such plants will be genetically
adapted to the climate and soils specific to the area. In addition, using truly
native plants will protect local native plants from inter-breeding with similar
plants from other regions (which can undermine the local adaptations native
plants have developed over time).
Unfortunately, the Red-osier Dogwood
sold here in nurseries frequently has been propagated from plants adapted to
growing on the East coast. Since most nurseries do not track the origin of their
stock, it can be difficult to know what you are getting, and you may prefer to
go to a nursery that knows their stock is from our region, or you can grow your
own.
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