Focus on a riparian plant: Douglas Spirea
Melissa Roberts
Douglas spirea enjoys status as one of the most visually appealing
plants used in riparian restoration projects. Towering pink flowers
resembling cotton candy cones bloom from June to September, brightening
up any reach of stream or field where spirea grows. Spiraea comes
from the Greek word, speira, which refers to wreaths, or garlands.
It is for this reason that species of spirea are often referred
to as bridal-wreath shrubs. Douglasii comes as a tribute to the
Scottish botanist David Douglas, who did much of his work in this
area.
Our use of this flowering shrub for restoration projects is not
the first time spirea has enjoyed fame as a useful plant. Native
peoples up and down the coast have used spirea in many fashions.
According to “Ethnobotany of Western Washington” by
Erna Gunther, Lummi people have used spirea as a way of spreading
salmon fillets for cooking, and the seeds have been used as a tea
for treating diarrhea. The wiry branches were bundled and used as
brooms for collecting marine dentalia shells. These tubular and
conical shells were so highly sought that they became a form of
currency for trading.
Spirea flourishes when its roots are wet. As such, it grows in
many riparian habitats including: swamps, mud flats, marshes, bogs,
wet meadows and stream sides. It is so successful in certain wetland
environments, that it can be considered an aggressive species that
has the possibility of wiping out other native vegetation. In varied
environments, however, spirea is a natural complement to other shrubs
and trees like ninebark, salal, salmonberry and willows. Douglas
spirea is listed as a national wetland indicator species, and is
useful for delineating wetlands. Often a pioneer species, spirea
sprouts quickly in clear-cuts, in areas where avalanches have wiped
out vegetation, or after a fire. One may find spirea growing from
Alaska to California, and east to Idaho and Montana. In optimal
conditions, the shrub can grow up to six feet in height, spreading
out its branches equally wide. Spirea will eventually form dense
colonies using rhizomes as a way of spreading. These thickets are
essential habitat for small animals seeking shelter, and as a food
source for animals such as black-tailed deer. Many birds, such as
the long-billed marsh wren, may be found nesting in these communities.
As with most flowering shrubs, butterflies, bees and other insects
are attracted to the plumes of flowers. While nectar is sparse in
this plant, pollen is aplenty.
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Other common names associated with Spiraea douglasii are used.
Most common is Douglas spirea, but also used are hardhack and steeplebush
(take a look at the flowers!). Other species of spirea have similar
leaf structure (elongated with hairy undersides), but have flowers
which can range from white to pink or purple, and are often shorter
and less pointed. Some species of spirea are cultivated and used
in commercial flower arrangements. As you can see, spirea is a useful
and successful plant to use for riparian restoration projects and
more.
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