My great aunt once told me that a very large rock she had traveled by countless times over the years had split by a seedling apple tree. (She very seldom traveled more than 50 miles away from the farm.) The five-foot boulder, sitting out on an open brushy slope, sheltered an old wild apple tree between its two halves. The roots would have had added protection and extra supplies of water collected from the surface of the rock, running down to the base. My aunt was very observing of natural things in her ‘field of vision’.
Several other accounts of this type have crossed my path. One is a photo of a large grave compartment that was split apart by an acorn (nut-seed of an oak), said to have been buried under the cement. Another was a split city sidewalk broken by an acorn that was placed under it.
Plants grow in many kinds of places, and in many kinds of physical situations. Seeds and spores of ferns will grow almost anywhere they end up, not necessarily having light at first but having moisture. They can grow from narrow divisions in sidewalks, from crevices in tree branches dozens of feet overhead, from bottoms of ponds, to cracks in vertical walls of rocky cliffs. They can even grow from fissures on the bottom side of over-hanging rocks.
Seeds dropped, placed or cached by animals and birds have virtually been planted. Spores not only travel by water but are also carried by air currents. They are light like dust and are carried by currents of air, floating to the remote north and south poles and to nearby cracks in over hanging rocks.
As I explored a creek flat near the mid-section of Kootenay Lake, looking for a certain fern species, I chanced upon another species growing from the underside of an over-hang on a cliff of sedimentary rock. I marveled at this hanging garden of Western Licorice Fern and its several clusters of 7 inch, dark green fronds dangling from this overhead ceiling of rock. The spores would have been lodged in the cracks by wind, germinated, and with adequate moisture seeping down from somewhere above – eventually producing beauty without flowers.
It seems that plants commonly found growing in rocky cracks are Ponderosa Pine and ferns. Several other species of ferns that also seem to favor growing in these “hard” places are Mountain Holly Fern and Rocky Mountain Woodsia (See Plants of the Southern Interior British Columbia (Idaho and Washington) by Parish et al.). Some people have tried transplanting such species, ending up ripping the foliage from the deep, impacted roots, and thus destroying the plant. It is very difficult to replicate their habitat in the garden.
Deep cracks in rocks, however small or large, conduct water from waterfall spray, seeps, spring snowmelt and rain, and store it while slowly releasing it through the seasons. Plants, including ferns, send out minute “tubes” which take up the nutrient laden moisture and, along with air, grow where most plants wouldn’t survive.