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Weeds of Concern:
Click on the picture or name of the
plant to see more information about that plant,
including control strategies.
Just a Pretty
Plant by Nancy Webber
People enjoy pretty plants. We landscape our homes and plant
flowerbeds. The horticultural trade looks for new plants and hybrids
to satisfy our desires. Many of these ornamental species come from
other parts of the world. Thousands of plant species have been
introduced over the last two hundred years. About 200 species are
now considered to be invasive weeds.
Here in Wyoming, with our long cold winters and hot dry summers, we
often times find it difficult to find ornamentals that grow well for
us. It’s exciting when we find a beautiful plant that thrives in our
harsh environment; it seems too good to be true.
Here is a look at six pretty plants, escaped ornamentals that are
now problem invasive weeds.
Tamarisk is a large
flowering shrub, also know as Salt Cedar. The “ornamental plant” has
a small, pink flower in finger-like clusters. Its green leaves are
slender, very similar to evergreen shrubs. There are a number of
beautiful examples of this plant around Lander and Riverton.
Unfortunately This pretty shrub has escaped the gardens and can be
found growing wild on reservoirs, along streams, canals, and in the
river bottoms. The large plants of Salt cedar can transpire well
over 200 gallons of water each day and will often dry up ponds and
streams. As this plant drops its leaves every fall it deposits salts
on the soil surface making its local environment even harsher to
other species. With the hot, dry summers and the increased damage of
the drought to the state this “ornamental plant” is one we need to
live without.
Dalmatian Toadflax and
Yellow Toadflax are examples
of weedy ornamentals that have escaped the flowerbed, this time to
invade rangeland. These plants are in the same plant family as
snapdragons, Yellow Toadflax also being known as Butter and Eggs.
The Toadflaxes are very hardy and thrive under dry conditions. Once
established it is very difficult to control, repelling herbicides
with it’s waxy leaves and resisting hand pulling with its
underground stems. Dalmatian Toadflax has escaped from flowerbeds
and cemetery plantings to infest areas around the Cemetery and Golf
Course in Lander as well as up the Squaw Creek drainage west of
Lander. Though toadflax is a designated noxious weed in the state of
Wyoming, it can sometimes be found in wildflower seed mixes and
needs to be watched for in those types of plantings.
There are many other examples of ornamental plants that have left
the yard and garden to cause problems elsewhere.
Purple loosestrife has moved
from perennial flowerbeds to invaded wetlands habitats in many areas
of the nation, including areas with climates much like ours. Many
consider this lovely plant the most environmentally damaging plant
that we have in the temperate regions of North America. It is not
yet established in our area and we need to be careful not to
introduce this problem into Fremont County’s valuable riparian
areas.
The Daisy is one of America’s favorite flowers, and there are a
number of beautiful native daisies.
Oxeye Daisy is a lovely
example of a non-native flower that has escaped from the garden.
This plant can survive over a wide range of environmental conditions
and habitats including grassland, overgrazed pastures, meadows and
roadsides. This pretty but noxious weed has already escaped from
contaminated hay to invade and dominate a riparian area along the
Wiggins Fork north of Dubois.
Common tansy is a European
plant introduced for its ornamental and medical properties. This
aromatic plant grows 1 to six feet tall, it has deeply cut,
fern-like leaves and yellow button-like flower heads. Common tansy
can be seen in many yards and gardens around Fremont County and has
escaped into otherwise pristine riparian areas throughout the
County.
The Russian
olive may be the best example of a good plant gone
bad. In some surrounding states and a number of Wyoming counties
this tree is considered a noxious weed and can no longer be sold or
planted. We love this plant because it is hardy, has fragrant blooms
and grows under less than perfect conditions (almost anywhere). It
is fast growing, attractive and works well in reclamation projects
and wind breaks. These characteristics make this tree/weed such a
problem. It grows almost anywhere, produces massive amounts of seed,
which is spread far and wide by birds out competing and replacing
important native species.
These plants invade otherwise healthy ecosystems and over time
replace the native vegetation. While they may be easy to look at,
these monotypic stands eliminate the food base for many other
organisms ultimately reducing species diversity and richness. The
second most significant threat to endangered species, nest to
habitat loss from development, comes from invasive species.
Watch out for plants that seem too good to be true. Truly more
trouble than they are worth.
Home owners are encouraged to plant species that are proven safe and
to replace those which have a potential to escape.
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