The Potomac Gorge

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You might be wondering, since I keep mentioning it, what the Potomac gorge is.  It’s an interesting geological/hydrological feature of the Potomac River: a 15 mile stretch from Great Falls to Theodore Roosevelt Island in Washington, DC, in which the river drops about 130 feet.  Great Falls itself is a plunge of 76 feet over about two thirds of a mile.  This is one of the longest and most dramatic fall zones of any watercourse on the Atlantic seaboard.  It’s the area where the hard metamorphic rock of the piedmont meets the sediments of the coastal plain, and as a transitional area supports a large diversity of life, including over 200 rare communities and species.

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One of the interesting geological features of the gorge is the bedrock terraces. These very hard rock formations are quite erosion resistant, and are swept by frequent floods, resulting in micro-habitats where you can find unusual species of plants.  Sometimes you can find plants growing next to each other that wouldn’t co-exist anywhere else in the world.  And there are species found in the gorge that are otherwise rare east of the Appalachians, like racemose goldenrod and Coville’s phacelia.

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More rare plants can be found in the Potomac gorge than in any other part of Maryland.

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There’s more.  A lot more.  When I started researching for this post I discovered some really nice articles, and spent hours reading, and decided I couldn’t do the topic justice on my little blog.  Most of what’s written here I found in the following sources:

“The Wildest Urban River: Potomac River Gorge”  –Jeffrey P. Cohn, Oxford Journals

Potomac Gorge Field Guide  –National Park Service

Potomac Gorge Site Conservation Plan  –Nature Conservancy

Potomac Gorge –Michael Kircher, Burn Magazine

Geologic Map of the Potomac River Gorge  –USGS

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Flower of the Day: Canadian Burnet

Sanguisorba canadensis; Rosaceae (rose family)

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First, an apology – the picture above is a little misleading.  The green branches behind the inflorescences are balsam fir, which makes for a poor photo illustration.  Sometimes I don’t have much of a choice, though.

The presence of balsam fir should be a clue that once again, I’m cheating.  I found this plant in Nova Scotia, and didn’t pause long enough for a proper photo shoot.  Here’s a look at the leaves:

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Canadian Burnet is native to the eastern US and Canada and the Pacific Northwest.  Though it does occur in Maryland, it is probably not a plant of the Potomac gorge; I’ve found references to it growing in Baltimore County and in the Blue Ridge, and west of there.  Sadly it is either threatened or endangered in nine states, including Maryland.

Burnet is a perennial that likes a wet habitat, though it is fairly drought resistant.  It will grow up to five feet tall.  Four other species (three native, one alien) of Sanguisorba are found in North America.

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In the past burnet sap was used to staunch wounds.  The genus name comes from Latin words meaning “blood” and “to suck in” (presumably that’s also the root of the word “absorb”).

Flower of the Day: Sevenangle Pipewort

aka common pipewort; Eriocaulon aquaticum; Eriocaulaceae (pipewort family)

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I’m cheating again.  Found these plants at the edge of a pond in Nova Scotia. According to the USDA, sevenangle pipewort can be found in Maryland – in Anne Arundel county – and in the District of Columbia, and Fairfax County, Virginia. The Maryland Biodiversity Project lists it in several Eastern Shore and northeastern counties.  So it could be in the Potomac gorge.  Next year I’m hunting for it.

Sevenangle pipewort is endangered in Indiana and Ohio as well as in Maryland. It ranges as far south as North Carolina, west to Minnesota, north into Manitoba, and all the way east to the Atlantic Ocean.

It’s aquatic: all the leaves grow underwater, and a single hollow (hence pipewort), multi-ribbed (hence sevenangle) stem emerges from the water to support the flower head.

There are other pipeworts, including tenangle and flattened, in the eastern US, about a dozen across North America, and more than 400 species worldwide.

 

Signs

Running low on subject matter – there is nothing left blooming now.  But I want to keep the blog going… Canadians put a lot of signs in their parks.  Here are a few.

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Bear, moose, coyote – cool! Let’s go look at some wildlife. From a distance.

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“Hike with friends and a solid walking stick.”  I had no idea coyotes were so aggressive.  Note the solid walking sticks parked by the sign for your use.  We saw a lot of that.  We borrowed them, but never used them to fend off coyotes.  When we found a sporting goods store in Ingonish we bought trekking poles.

 

 

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Wait, what?  Aggressive hawk? Are you kidding me?  I would love to know what incident prompted this sign.

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Hmm.  Dangerous cliff.  No kidding.  But I like the graphics.

 

 

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Okay, this I can see how this might not be obvious.

 

 

 

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This was from Hopewell Cape on the Bay of Fundy in New Brunswick.  The tidal bore is pretty damn impressive.  “Find a comfortable rock…”  And DO NOT PANIC is always good advice.

 

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They’re really not kidding about it.

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And here’s a classic from Dolly Sods, West Virginia.  Now this is something worth posting a sign about.  “If you did not drop it do not pick it up.”  Remind me to tell you about the live grenade my next door neighbor had as a World War II souvenir.

Flower of the Day: Bunchberry

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Cornus canadensis; Cornaceae (dogwood family)

Now I’m cheating.  According to the USDA, bunchberry can be found in Maryland.  But it’s a northern plant that doesn’t like the heat and humidity of mid-Atlantic piedmont summers (I should know, I’ve tried growing it often enough), so you won’t find it in the Potomac gorge.  You might be able to find it in the westernmost part of the state (Garrett County), at the higher elevations. Or maybe not; it’s endangered there, as well as in Indiana and Illinois.  And it’s threatened in Iowa and Ohio.

This one I found on Cape Breton Island, Nova Scotia, in September (very unusual for it to be blooming so late in the year), in the boreal forest region.

Really looks like our common flowering dogwood (Cornus florida), doesn’t it? But it isn’t a tree or shrub; it’s a groundcover, standing less than a foot high.

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More Seeds

Milkweed (Asclepias).  Didn’t see the plant in flower, so I can’t say which species.  October 28, Shenandoah National Park, parking lot at Riprap Hollow trailhead.

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closeup of seeds

 

 

 

 

 

 

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unripe pods not quite ready

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fly!  be free!

 

 

 

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I just love how they form little balloons as they’re getting ready to go…

 

 

 

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…and embrace the sky