Nature

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The Seeps of Lewis County:  A Hidden Natural Treasure

By Cynthia Rhorbach

Some Lewis Countians know of the secret places along a creek where water seeps from the ground year-round, providing homes for rare plant communities and places of solitude and wonder for admirers of nature’s mysteries.  Lewis County is recognized by the State of Tennessee for its seeps, three of which are designated State Natural Areas – Dry Branch, Auntney Hollow, and Langford Branch.

These three natural areas are special because they protect populations of a state and federal-listed endangered plant, the Tennessee Yellow-eyed Grass (XyrisXyris tennesseensis as seen in Validity Magazine, December 2011 tennesseensis).  This rare plant is found on five additional privately-owned properties in Lewis County and nowhere else in the state. The number of sites where Xyris once existed has likely declined from changes in land use, rural development and other human pressures.

The seeps occur on slopes, varying from steep to nearly level, along headwater streams of the Western Highland Rim, the physiographic province where Lewis County is located.  The headwater streams often erode down to the calcareous, cherty bedrock of the Fort Payne geologic formation.  Seeps and cold springs contribute significant amounts of water to the total volume of these streams.  Even during periods of drought, the headwater streams continue to flow in Lewis County.

Groundwater comes to the surface in a seep and slowly flows over a shallow, mucky, gravelly and slightly alkaline soil. This shallow soil provides a layer for the seep plants to root. Underneath the shallow muck is bedrock that prevents large, deep-rooted trees from moving in.  Woody shrubs like Willow (Salix spp.), Alder (Alnus serrulata) and Swamp Dogwood (Cornus amomum) will grow around the seep margins, leaving the interior relatively open to sunlight.

The openness and light allow the Yellow-eyed Grass to thrive with two other rare Parnassia-Xyris, Validity Magazine, Hohenwaldplants – the Largeleaf Grass-of-Parnassus (Parnassia grandifolia), a state-listed threatened species and the Short-headed Rush (Juncus brachycephalus), a state-listed plant of special concern.  Botanically speaking, neither the Grass-of-Parnassus nor the Yellow-eyed Grass is a true grass.

The person who named the Grass-of-Parnassus must have thought the seeps where it grows to be very special.  Parnassus was one of the most sacred Greek mountains where a holy fountain gave the gift of poetry to those who drank from it.  Perhaps the water in the seeps could do the same.  It does keep these precious rare plants alive!

Some of the other plants growing in the seep habitat are:  a variety of Black-eyed Susan (Rudbeckia fulgida var. umbrosa), Cowbane (Oxypolis rigidior), Roughleaf Goldenrod (Solidaga patula), Seedbox (Ludwigia alternifolia), Marsh Fern

Parnassia grandifolia in Validity Magazine, December 2011

Beauty on Swan Conservation Trust land exceeds expectations.

(Thelypteris palustris), Smooth Phlox (Phlox glaberrima), Bulrush (Scirpus atrovirens), Flat Sedge (Cyperus strigosus) and Beak Rush (Rhynchospora capitellata).

Although certain seeps have been found to be a hospitable habitat for Tennessee Yellow-eyed Grass, this finicky plant does not grow in most of them.  It is more common to find the seeps than it is to find the Yellow-eyed Grass. Most of the time, only its companion plants are abundant, presenting an unsolved botanical mystery.

In the southeast corner of Lewis County, Swan Conservation Trust has been protecting numerous seep habitats on Big Swan Headwaters Preserve since its creation in 2004.  A recent survey of wetlands on the 1,475-acre preserve revealed a variety of seeps inhabited by an interesting mix of wetland plants, most notably, large numbers of the state-listed threatened Largeleaf Grass-of-Parnassus.  Although no Xyris was found anywhere, several of the Preserve’s seeps may serve as potential candidate sites for experimental restoration of Xyris in the future.

The remote forested locations that are havens for seeps and rare plant communities are also peaceful places of undisturbed natural beauty in all seasons of the year.  A wide variety of wildflowers common to the Western Highland Rim adorn the slopes and stream banks in spring, summer and fall.

The three State Natural Areas provide perpetual protection for the seeps with endangered Xyris through their designation as Class II Scientific Natural Areas.  They will always provide important places for scientific research and study.  Most of all, they provide an opportunity to discover the reasons for the scarcity of Xyris and to learn about the special qualities of the Lewis County seeps that keep rare plant communities alive.

Cynthia Rohrbach is a biologist with a 20-year career as a science teacher followed by a 12-year position as an environmental specialist with Tennessee Department of Environment and Conservation.  She is also a founding board member and former President of Swan Conservation Trust.  For more information about Swan Conservation Trust, visit the website.  To arrange a visit to Big Swan Headwaters Preserve, call the Swan Trust office at 931-964-4402.

 


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