May 21, 2016

Birch-leaved Spirea

Birch-leaved Spirea
Spiraea betulifolia
Rosaceae (Rose Family)

Quick ID
Yarrow (left) vs. Spirea
This wild spirea is usually classified as a shrub, although it doesn't typically take on the shrubby, fit-for-a-hedgerow form of its fancy cultivated cousins.  It is a showy little flower though, borne on a woody stem whose bark tends towards cinnamon colors and gets a bit shredded with age.  The leaves are alternate, oval with coarse teeth along the tips, mellow green with pale undersides.  Don't mistake the leaves for those of serviceberry (Amelanchier alnifolia), which are more heart-shaped at the base.  And don't mistake the flowers for yarrow (Achillea millefolium) either!  Birch-leaved spirea flowers are creamy off-white, arranged in flat-topped clusters called corymbs, and have waggly little stamens that reach out past the petals like so many antennae.  The whole shebang is generally  around 18" tall but grows up to 30" in some places.

Birch-leaved spirea has a showy cousin (Rose Spirea, S. douglasii, aka hardhack) that's a treat to find.  The flowers are a rich pink, arranged in sweet ice cream cone-shaped panicles.  Look for it forming dense riparian thickets up to 6' tall in the far northwest corner of Montana.
Rose Spirea
Where's it Found?
Fall color
Look in mid-elevation foothills and montane zones of the intermountain west.  Eastern WA and OR, western MT, southern ID, even in the Black Hills of South Dakota.  Here in Montana, I think of Doug Fir, Lodgepole and Ponderosa slopes, dappled shade, Ninebark understory.  This is a very adaptable wildflower, growing in moist or dry sites, out in the open or in shaded forests, from the foothills to the subalpine zone.

What's in a Name?
The common name spirea (pronounced spy-REE-ah) comes from the Greek speira for spiral or anything twisted, and references this flower's long tradition of gracing garlands.  The species name betulifolia literally means "birch-leaved," and the leaves do indeed look a bit like a swamp birch.  There are quite a few species of Spiraea, and many of them are known colloquially as "meadowsweet."  Spirea contain salicylates, which are the naturally occurring predecessors of our modern day aspirin.   They were first isolated from the meadowsweet now known as Filipendula ulmaria, which was once classisified as a spirea...hence the name, aspirin!

I first decided to write about birch-leaved spirea because of the drought.  Last summer (2015) western Montana  Effects on the local flora were impossible to ignore.  An extremely warm winter followed by a bone dry spring sent the wildflowers into a panic.  Fearing doomsday, they flowered and set seed as fast as possible, leaving us botanists harumphing.  We started picking huckleberries in early June, and full six weeks too soon.  By early August the fall colors were already crackling in the 100°+ heat.  A dry and crispy summer where it seemed hardly anything kept its will to bloom...except spirea.  The birch-leaved spirea seemed to be doing fine, even thriving.  I can only imagine how happy the pollinators were for that sweet, elusive sip of nectar.

Wild Gardening
Spirea grows and spreads from its super-strong rhizomatous root system, rather than seeds, for the most part.  If you want to propagating it, try root stock or even layering stems.  Try part shade, although it's pretty adaptable.  Deer will eat it, but they don't LOVE it.  The USFS Fire Effects Information System (a SUPERB reference, btw) lists it as fair to poor forage for all the large grazers.  As a mid-summer bloomer, the native bees absolutely adore spirea, and you can always find a host of interesting bugs investigating the landing-pad flower tops.  Spirea has always made me think of granny cottages and comfy summer afternoons, both of which I love.

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