Walking Across Boulders

File:Alvar2.JPGBy Allison Vaughn

During winter months, I take literally hundreds of photos that (upon a quick scan of each folder) all look the same: golden grass, gray trees, blue skies, dolomite boulders. I like the structure of the winter landscape, the silvery old growth chinquapin oaks, the open-grown post oaks, and the exposed geology.

I’ve taken so many winter woodland and glade photos that my slideshows can be, um, predictable:

“Looks like grass,” he says.
“No, but look! It’s a huge glade (with an average FQI of 4.9-5.5)!”
“Sort of looks like an old field…”

Winter landscape photos can be truly stunning, but photos of spring in the Ozarks commands a wider appreciation.

After seeing the morning cloaks and little brown bats flying around during the spate of clement weather, I went on a search in deep, forested coves of the northern Ozark Highlands to look for the first leaves of spring wildflowers to find one anemone in bloom alongside a frequently traveled trail. Aside from the strange little area around Bagnell Dam where spring wildflowers bloom almost two weeks before the rest of the wildflowers in the state, I appreciate true forest in early spring for the early wildflower displays. But I cherish forest in the winter when the ferns and mosses remain brilliant green, even in snowpack, when the woodlands are a uniform brown.

So I spent an appreciable amount of time this afternoon scanning through my winter photos from the past three years, sitting cross-legged in my chair so long my foot fell asleep. I opened each folder and quickly looked for green. I saw almost 500 various moss photos, possibly every commonly encountered moss in Missouri. Many of the moss pictures look just like this one:

Variations on a theme.

If I were diligent, I would copy all the moss photos into one folder with the location and date of each photo so that when I needed a moss photo, I could go directly to a single folder. It’s precisely this diligence that I lack, and am therefore in the situation I am this afternoon when I want to write about walking ferns. Like moss, walking ferns intrigue me, and I take photos of them almost every time I see them. I have great diagnostic photos of them and all their parts, but the walking fern photos are buried in folders, mixed in with other green things. I thought I could always find walking ferns in folders of photos taken in late winter when I migrate to anything green.

Alas, I’m stuck with this mediocre and over-lit photo taken last week in the forest, the only green photo I took that day.

With a widespread distribution in Missouri, and known from likely every county in the Ozark Highlands, walking fern Asplenium rhizophyllum inhabits moist calcareous boulders in shady woodlands and forests. It can grow through thick mats of moss, dependent on the constant source of moisture in limestone, dolomite and less commonly on sandstone. Walking fern possesses a truly fascinating ability to produce small plantlets at the tips of mature blades. Often in the Ozarks, one can find a boulder literally covered with walking ferns of various age classes and sizes, large plants surrounded by plantlets where the leaf tip landed on the moist rock. In the lousy photo above, one small plantlet can be seen in the right hand corner where the leaf tip hits the moss. The sturdy, exposed white rootlets of the very young plantlets penetrate the moss layer to reach the rock substrate upon which they will remain.

Ferns of the genus Asplenium can readily hybridize.  Asplenium x kentuckiense is a cross between A. platyneuron and A. pinnatifidum, and is loyal to sandstone bluff crevices. Both A. platyneuron and pinnatifidum occur in Missouri, but I’m unsure whether anyone has discovered the sterile hyrbid in Missouri. Of course, like all cool plants, kentuckiense can be found in the Arkansas Ozarks (because they have more sandstone crevices than we do). Asplenium x herb-wagneri is another Arkansas-but-not-in-Missouri Ozarks hybrid; another sandstone Asplenium, this one is a cross between A. pinnatifidum and A. trichomanes. Both parent species occur in Missouri. LaBarque Creek country has the potential to harbor these hybrids.

On a warm February day in 2008, I went to one of only a handful of Missouri locations of Asplenium x ebenoides, a cross between walking fern and A. platyneuron. A. platyneuron is at home in dry woodlands as well as old fields. A. ebenoides takes on the walking fern’s habit of living in limestone boulders, but does not have the ability to form little plantlets from the mature tips. Nevertheless, we hiked for an hour through nice chert woods to the historic population of this fern to find no fern. My fieldmate had seen the cross in this location for 20 years, but only walking fern was present, no ebenoides. Unfortunately, my fieldmate said it was likely jacked by a botanist. Very uncool treatment of a very cool plant. I’ll keep looking and if I ever find it, I promise to take a better photo.

Allison Vaughn is the author of the blog The Ozark Highlands of Missouri
This article was reblogged with permission.

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2 responses to “Walking Across Boulders

  1. Thanks for finding this Jill … walking ferns might be my favorites, they are so small and adventurous. And Alison’s passion for these lovely small details, like moss and lichen and fungi and ferns makes me feel less odd!

  2. Well said, Sara! Allison’s postings on botony are always a joy to read.

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