Sunday, March 3, 2013

Special Plants, Special Places - Outcrops

Some plants are found in many places – tuliptrees (Liriodendron), sweetgum trees (Liquidambar ), red maples (Acer rubrum), Canadian goldenrod (Solidago canadensis) and others are everywhere around me. But some plants are only found in special places. Places that have just the right environment, the right minerals, soil levels, moisture levels and other special characteristics. I visited just such a place last week – a place known as an “outcrop”.

Diamorpha in Dicranum moss

After I visited that area, I happened to pick up my 2012 issue of Tipularia, The Journal of the Georgia Botanical Society. The first story in the issue is “Piedmont Outcrops, Overgrown and Under Fire.” The author explained that “granite outcrops of the southeastern United States are a treasure-trove of rare plant species.” The first picture in the article showed two of the plants I had just seen: Diamorpha smallii and Tradescantia hirsuticaulis. It was interesting to read about the very difficult conditions that these outcrops create for their resident plants. High temperatures and thin soils require specially adapted plants. Some plants grow when moisture is plentiful and then die out during the hot months, leaving seeds for the cycle to start again later.

Outcrop fringed by grasses and trees
When I first entered the area, it was like entering a meadow in the middle of a forest – a big clearing with some dried grasses on the edges. As my eyes adjusted to this unusual sight, I realized it was a huge area of rock, covered in some areas with moss and low growing plants and exposed in others as bare rock. I could quickly see from the color variation that even the moss population was diverse: I recognized the lush bright green of Dicranum scoparium and the dark, grey areas of Grimmia laevigata. Mixed in were some pale green lichens and at least 3 other species of moss. These plants, which benefited from small collections of soil on the rock themselves, now provide areas for seeds to gather and sprout.

Diamorpha smallii in Grimmia laevigata
Throughout the area was the small annual sedum known casually as “diamorpha” (Diamorpha smallii) or Small’s stonecrop. Only the leaves were present now; it will bloom later in the spring with small, starry white flowers reminiscent of other native sedums. Even without blooming, the succulent red leaves offer stunning color and beauty on the bare rocks and mixed into the moss. In areas of deeper soil, more perennial plants like the hairy spiderwort (Tradescantia hirsuticaulis) and grasses were found. Even a few trees had managed to survive over time (including some stunted invasive privet and Japanese honeysuckle).

Small vernal pool surrounded by mosses and Diamorpha

In one area was a small pool. Floating in the pool was more Diamorpha. Dried tuffs of moss surrounded it, no doubt waiting to be reinvigorated with the next spring rain. The whole effect was quite beautiful, as if we had stumbled upon a fairy world.

Diamorpha floating in pool, tethered by a long stem
Georgia is a unique place for granite outcrops. According to the article in Tipularia, “Approximately 87% of all granite outcrop habitat area occurs in Georgia and the majority of outcrops exist within sixty miles of Atlanta.  If you are interested in exploring an outcrop in Georgia, here are some suggestions:

In the month of March, several areas are sponsoring an event known as Monadnock Madness to help people learn more about these special places. The event is described on their website: “In March (2013), you can experience these unique places first-hand through guided hikes and free tours at Arabia, Panola, and Stone Mountains. If you can conquer all three peaks during the month you’ll earn a special souvenir that you can wear as a badge of honor.” 

Check it out at the hotlink above and take this opportunity to discover some of Georgia's unique natural environments.

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