Wednesday, March 21, 2012

Searching for color in a gray-and-brown world

With the recent warm weather, I've been thinking a lot about wildflowers.  So I made a trip to Curt Gowdy State Park on the east side of the Laramie Range (7000 ft elev) in search of spring plant color in a setting of Precambrian granite.  Once there, it hardly felt like spring -- the park was deserted, Granite Springs Reservoir was still frozen, and the aspen were leafless.  Still, most of the snow was gone and, as John Muir would say, it was indeed glorious to be on the trails again.  I kept my eyes on the open south-facing slopes hoping to catch a flash of yellow (sagebrush buttercup) or white (Easter daisy), but except for some green grass, everything was gray or brown.
Leafless tree and Sherman granite, a Wyoming spring vignette.

Well ... not quite everything.  The Sherman granite shone tastefully in the spring sun, with pastel pink feldspar crystals and bits of sparkly quartz and biotite.  The fantastical shapes of the tors against blue sky were as enchanting as ever, and of course the pines had kept their dark green needles all winter, getting in a bit of photosynthesis whenever temperatures were warm enough.  But I was in the mood for brighter color.

To right and below: Proterozoic Sherman granite; emplaced 1.4 billion years ago just south of the Cheyenne Belt, where Proterozoic terranes had been accreted onto the southern coast of North America only a few hundred million years before.

Whenever the trail dropped into a drainage, I found stands of hardwoods, all still without leaves.  But wait ... what are those red spots? (click and look carefully to view)

 ... buds! ... the beginnings of the year’s growth, enclosed in bright crimson bud scales.

I know this plant, but I decide to use it to test the Winter Tree Finder.  This is a simple dichotomous key -- a series of choices that eliminate a subset of trees at each step, finally arriving at the correct determination (for more, see this post).  Starting on page 6, I’m asked whether the tree is a conifer ... or not. It's not.  Proceeding step by step, I note that my specimen has leaf scars opposite on the twigs (and branches arranged similarly as you can see to right), narrow twigs, narrow leaf scars and a single type of bud, bringing me to the maples. Here I have to stop, as the Winter Tree Finder is limited to eastern and midwestern North America.

From Nature Study Guild Publishers
But this is not a problem -- there are just two maples in Wyoming and one, the big-tooth maple, is found only in the southwest part of the state.  So this is the Rocky Mountain maple, occasionally a small tree but usually a large shrub with many densely-clustered stems.  It is widespread in western North America, and grows farther north than any other New World maple -- from southeast Alaska, British Columbia and southwest Alberta south to southern California, Arizona and New Mexico, and east to northwest Nebraska and western South Dakota.
Rocky Mountain maple, Acer glabrum, ready for Wyoming spring ...
... and decked out for summer in New Mexico; from Vascular Plants of the Gila Wilderness .

Additional Information

Curt Gowdy State Park has a nice network of trails for touring the Sherman granite, open to hikers, bikers and dogs.  There are equestrian trails and facilities as well.  Maps and additional information are available online.

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