Field Notes—

Ferns: The Great Unfolding

By Curtiss Clark

In the natural world, spring is a great unfolding. Tender buds split their seams like overladen luggage, laying out their trousseau of leaves and blossoms to freshen in the sun. Pupate insects unpack legs and lacey wings like alien landers dropped in from somewhere beyond our ken. And everywhere trap doors fly open from the vast underground empire of roots and rhizomes to launch green armies of chlorophyll across the dead landscape to join forces with their old ally, the sun.

Few living things unfold into existence with the elegance and grace of the fern. It may just be that practice makes perfect, since ferns have been unfurling themselves in spring for hundreds of millions of years. Along with their less stately clubmoss cousins, ferns were among the first vascular plants with the capacity to circulate water and nutrients throughout their systems, unlocking new possibilities for photosynthesis through both increased size and more elaborate architecture.

Consider the fern’s place in the lineup of evolution’s great parade. First came all the single-celled microscopic pioneers with alga, pondscums, seaweeds, and kelps marching behind. From this fertile stew, molds, yeasts, and fungi flung or floated spores across the dividing strand of water and land, giving solid footing to subsequent spore spawners, including mosses and liverworts. With its innovative vascular system, in time the fern literally rose above the rhizome rat race below to cast its spores a little farther afield.

Imagine a world of just mosses and ferns before the evolution of all the seed-bearing plants that now crowd our landscapes — a planet of water, hard rock, and green fuzzies, with the culminating glory of those earliest of early springs: fern fiddleheads unfolding into levitating lattices. Ferns were the first plants with roots, stems, and leaves.

And what beautiful leaves they are. There are species of ferns with names like Adder’s Tongue or Curley Grass with leaves or fronds that don’t look all that fernlike. But most familiar fern leaves unfold in the general shape of a Christmas tree and are — in the parlance of avid fern fans — once-cut, twice-cut, or thrice-cut. Once-cut fern leaves are segmented in simple leaflets. Twice-cut fern leaves have leaflets that are themselves cut into subleaflets. And the laciest thrice-cut ferns have leaves with leaflets, subleaflets, and subleaflet lobes. For a novice world just beginning to experiment with leaf design, Earth started strong.

All these eons later, ferns vie for the favor of the sun with a plant kingdom that has unpacked everything from artichokes and aspens to zebra plants and zinnias. They now sit quite comfortably in the dappled shade of their competitors unfolding as they always have to a new world every spring.

(This and more than 65 other “Field Notes” essays are available at www.field-notebook.com.)