Three species of ferns found for the first time in South Carolina at Lake Jocassee

Patrick D. McMillan, PhD

I am constantly surprised by the diversity we have yet to uncover in the Jocassee Gorges. One of the most profound discoveries was made over 80 years ago by botanists, William Chambers Coker, Henry Totten when they uncovered ferns such as Appalachian Filmy Fern (Trichomanes boschianum) which are from tropical families and Mary Taylor who found Tunbrige Fern (Hymenophyllum tunbrigense), a tropical filmy fern, growing far from its nearest location in Jamaica along the gorges of the Eastatoe River. Since then a second tropical disjunct was located, Single-sorus Spleenwort (Asplenium monanthes), reported by Blomquist (1945). Only one other similar addition was made in the general area when John Townsend and Steven Platt located what they thought was Wright’s Cliffbrake (Pellaea wrightiana) growing on an outcrop near Sunset, SC. When that specimen was scrutinized it turned out to be misidentified and actually represented a much more impressive addition, Arizona Cliffbrake (Pellaea ternifolia ssp. arizonica) – the first record for eastern North America of this desert fern. The discovery made during the first weeks of December 2017 have to be added to the great chronicles of fern discoveries in the gorges and are among the most profound of my career.

During our November first Sunday expedition, Kay Wade informed me that she had found what she thought was Purple Cliff Brake (Pellaea atropurpurea) growing along a man-made cliff on the lakeshore. I was surprised to hear this as that species is limited to limestone and calcium-rich amphibolite and the cliff she was referring to was granitic and highly acidic. During our first Sunday expedition on December 3rd, she and Dan Whitten, who had also seen the plants on a prior trip, decided to take us to the cliff to see the plant. I recognized the plant from 50 feet away as definitely not being Purple Cliff Brake but rather Wright’s Cliffbrake! Here we were looking at what we would soon realize was a population of over 2000 plants of a desert fern normally found in Arizona and western Texas! This species is known from only two small populations in the eastern United States, both in the piedmont of North Carolina. What a day! I quickly spread the word to my botanical friends and we soon found ourselves back out on the lake looking closer at the site and taking photographs with Richard Porcher and Edward Pivorun. While gazing up the cliff-face I was completely shocked to find yet another incredible and unexpected fern – Wavy Cloak Fern (Astrolepis sinuata ssp. sinuata)! This is another desert fern known only from one other location east of Texas, Meriweather County, Georgia. I was astonished to find out that this plant was represented here with somewhere between 400 and 500 vigorous clumps. Further scrambling along the base of the cliff allowed me to find what may be the most surprising fern, a third desert species – Copper Fern (Bommeria hispida)! This is the very first record of this incredible and tiny fern with triangular fronds in the eastern United States.

While we could easily access a few of the plants of Wright’s Cliffbrake the Cloak Fern and Copper Fern could only be viewed through binoculars. We returned on December 14th with a younger member of the group and expert climber, Cody Davis. Cody easily scrambled up the rock and we now have a few fronds of each species dried and in the herbarium at Clemson University to officially document these incredible ferns as new to South Carolina and one as new to the eastern United States.

Now the big question is, how did they get here? The site where the ferns are located is granite cliffs that were created by humans during the construction of the Jocassee Dam in the late 1960’s-early 1970’s. The entire hillside was blasted, quarried and denuded of all vegetation – completely! You can see the site during construction by watching the first minute and a half of the movie Deliverance. The question of where they originated may never be solved but there may yet be other populations found on the natural outcrops around the lake. A local source would seem most plausible but there are other explanations. The three ferns found on this cliff are quite abundant in the desert Southwest and they are constantly shedding spores that could make their way into the upper air currents and settle here in this horseshoe-shaped, enormous cliff-face. The desert ferns are found on southwest and western exposures but the shape of the cliff forms a cove and even provides a north-facing exposure where we located another Pickens County record, Southern Shieldfern (Thelypteris kunthii) growing just above the water surface. The moderation provided by the lake, the drainage provided by the cliff and the unique weather of the area in general have all come together to transform something that was in fact the destruction of an entire mountain by us in 1968 into a paradise for ferns that are known nowhere else in our state. What a story.

I speak dozens of times a year, all over the country about the uniqueness of the Gorges region. I now have an even richer story to tell. This area is well-known for its fern, bryophyte and overall diversity. It may now rank as the richest fern flora in the Appalachians and indeed in the USA, with 62 species just within the gorges of this small area of western Pickens County, where the recent discovery was made. It is astonishing that the variety of microhabitats and microclimates of this unique landscape have provided habitats for plants more at home in Jamaica, Veracruz and Arizona! What a wonderful world we live in and what a precious gem we have in the Jocassee Gorges!

 

One Comment on “Three species of ferns found for the first time in South Carolina at Lake Jocassee

  1. Could I please be on your list for sending out interesting things about plants. I used to live in Newberryand loved the plants there!

    Like

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