Thursday, February 21, 2013

The Hocking Hills and a Very Rare Fern

I'm always on the hunt for the next rare plant to cross off my life list.  Whether it's a thousands miles away and requires a long, carefully planned journey or just a ways down the road, all experiences are unique and worth the effort in their own respective ways.  This past weekend your blogger found himself with a mild case of the winter blues and decided what better way to break out of it than to get out for some hiking.  So I layered up, threw some boots on, and headed out with the specific task of finally visiting a secretive site with one of Ohio's rarest vascular plants.

A sudden but welcome snow band that dropped a couple inches very quickly

The drive from my residence to the Hocking Hills region is one of the most scenic and enjoyable in my section of the state.  Winding county roads take you through numerous hollows and ridge tops; each with wonderful views perfectly representing southeast Ohio.  As I neared my destination a sudden but welcome snow band moved through and quickly dropped a couple inches of fresh white powder.  The already stimulating drive instantly turned into one of the most memorable in recent memory.

Gorgeous winter wonderland under the Hemlocks

The surprise snow left behind a gorgeous winter wonderland that was artfully captured by the evergreen hemlocks and rock outcroppings.  The snow stuck to the branches and contrasted handsomely against the dark green needled canopies.  Eastern hemlocks have always been one of my favorite species of trees with their cinnamon brown bark and aesthetic growth form.  They abound in the cool, moist forests of the Hocking Hills and only add to the intrinsic value of the landscape.

Snow covered hemlock
Hemlock needles

The Hocking Hills are widely known for breathtaking gorges, cliffs, and rock shelters/houses cut out of Blackhand Sandstone; a particularly weather-resistant and consolidated formation of sedimentary rock.  Places like Conkle's HollowAsh Cave, and Cantwell Cliffs famously show off these geologic wonders and their accompanying plant communities.  Within a very select few of the region's sandstone alcoves and overhangs lives the bounty of my search: the Appalachian filmy fern (Trichomanes boschianum).

Appalchian filmy fern (Trichomanes boschianum)

In the darkest recesses of this particular alcove are the petite and dainty fronds of the filmy fern.  This small patch is one of only three populations known in the entire state; all occurring within the Hocking Hills and in quite close proximity of one another.  It timidly grows from the sandstone ceiling with its roots tucked tightly into the cracks and fissures, feeding directly off groundwater that continuously seeps in from above.

Appalchian filmy fern (Trichomanes boschianum)

Don't let looks deceive you.  Each frond is only a few inches long and excruciatingly thin with some parts of the plant only one cell thick!  Its evergreen nature mixed with the surrounding associate mosses and liverworts give a flash of color from the shadows even during the grey winter months.

Trichomanes boschianum North American distribution: courtesy BONAP

You would think with this fern's special habitat niche of cool, moist caves and alcoves in non-calcareous rock dominating the area that this plant would be much more common but that's curiously not the case. Consulting a map of its natural distribution you can see the Hocking county record in Ohio is quite disjunct from any others and is currently the most northern station known.  You have to travel a hundred miles or so south into Kentucky and West Virginia before it occurs again.  Ohio botanists have looked for years in every nook and cranny they can access with very little success at discovering additional sites.  Luckily a couple years ago a friend of mine doing his masters work on the flora of Crane Hollow did manage to find only the third known population of this fern in a rock shelter high above the gorge's floor.  If there's more to be found you can bet they are in similar, nigh-on-unreachable places.

Being 'more' common to the south, I would hypothesize this Trichomanes moved north during a warming period and settled into appropriate habitats in extreme southern and southeastern Ohio.  Once the climate shifted again to something more unfavorable, the ferns northern extension died back but luckily the Hocking Hills acted as a refuge and allowed these small populations to hang on today.

Appalchian filmy fern (Trichomanes boschianum)

In a perfect world I'd love to share the locations for plants like these so others could see and experience its dainty charm for themselves.  Unfortunately due to its extreme rarity combined with a very fragile ecosystem/existence it's best this little fern be left alone and unknown to the masses.  Even the slightest of alterations could quickly spell doom for it from too much human interaction.

Appalchian filmy fern (Trichomanes boschianum)

It's not only people but nature itself that could just as easily erase it from this small, cramped grotto.  If the subterranean water supply should ever cease or a change in humidity and shade occur, you can bet this plant would be gone in no time at all.  Its future existence seems to balance on the edge of a knife and I hope it continues to beat the odds and cling tenaciously to that sandstone ceiling.  It would be a shame for our state's biodiversity to lose out on such a fascinating and charming little fern.


  1. Such a lovely little fern, and one I will never find in NY. Thanks for making the effort to find and photograph it.

  2. You are soooooooo lucky to have this fern anywhere near you. Great shots -- keep up the good work!