A Very Rare Fern

Along with Jarel Hilton and Dave Minney, I participated in the fifth Hocking Hills Christmas Bird Count. We found lots of birds, including White-winged Crossbills, Pine Siskins, Red-breasted Nuthatch, and Hermit Thrush. This count is really excellent, and you may wish to put it on your radar screen for 2010.

Fortunately for me, Dave and Jarel are great all-around naturalists and general biodiversiasts (I have coined a new word!). And it was much to our pleasure and good fortune that I realized that one of Ohio's only two stations for the incredibly rare Appalachian Filmy Fern, Trichomanes boschianum, happened to be in our assigned area.

This semi-subterranean beauty was a "life fern" for both of them, and I was most curious to see what it looked like in winter, so we detoured over to the top secret locale where it grows. Not all was naught on the ornithological front in regards to this detour, either - upon exiting the car, Jarel spotted a female Sharp-shinned Hawk high overhead. These gorgeous and savage little raptors are easily enough missed on CBC's.

The sandstone alcove where Appalachian Filmy Fern grows. A small patch of this strange plant hangs from the ceiling in the deepest shadows of the recess, where sunlight never strikes and its feet remain damp due to a constant seepage.

We move in closer, our visibility aided by the flash of my Panasonic. Filmy Fern grows in tight clumps, and each frond is but four inches or so in length. One would think that with the abundance of sandstone outcrops and attendant grottoes such as above, this fern would be in numerous locales. Such is not the case. Botanists are no fools, and a great many of these sorts of places have been searched, to no avail. Just last year - or maybe the year prior - one other small population was discovered (really rediscovered) a few miles away. That's it. And this is why I can't divulge the exact location, other than to say Hocking County. But now that you've gotten a taste for the habitat, perhaps you'll go on to find some other stations for Appalachian Filmy Fern.

Here's the total North American range of Trichomanes boschianum. Twelve states, and it is endangered or threatened in six of them. It is also found locally in Mexico. Trichomanes is a tropical genus, with dozens of species elsewhere in the world.

Deep in the subterranean gloom, the delicate fronds scallop the sandstone roof in the manner of a moss. And there is plenty of the latter in the damp perennial darkness of these sites, including quite a bit of large showy liverworts. Getting decent photos of filmy fern is challenging; one must get the flash just right to avoid overexposure or underexposure.

Up close, the "filmy" part of the name makes sense. The tissue is very thin and flimsy; practically like rice paper. Appalachian Filmy Fern leads a tenuous existence here at the absolute northern reaches of its distribution. Threats are threefold, at least. If a small grotto like this one is "discovered" and heavily exploited by people clambering about, the fern is likely to be scrubbed right off the ceiling.

Prolonged drought can have ill effects. If poorly understood subterranean aquifers go dry, and the constant seeps that percolate into filmy fern habitat disappear, so will the fern.

Finally, extreme and prolonged cold snaps can whack filmy fern colonies, perhaps permanently. On this last score, the future may be rosier if mean winter temperatures continue to rise.

In an exclusive, here is actual Appalachian Filmy Fern video - maybe the first on the 'net! You may notice that the company from whence I downloaded this video software wants me to but their goods - no!