A little over 10 years ago, I had a job as a survey biologist. My duty was to walk endless lines through the boreal forest, stopping at set intervals to count everything that was alive that wasn’t a tree. It was a brutal job in many ways, but what it did leave me with was an endless fascination with the things most people tend to overlook. Every day for four months, I would carefully study half-meter square patches of the forest floor and marvel at the diversity of life that usually end up crushed underfoot as we hike to some breathtaking vista or stalk the woods for a glimpse of a moose or a bear.
Even though since that summer, I devoted the rest of my research years to studying ‘charismatic mega-fauna’, it’s become sort of a ‘thing’ with me to notice all those plants and animals that everyone else seem to miss.
Today it’s horsetails, those spindly green rush-like plants that seem to pop-up everywhere once you start noticing them. Sometimes the bane of gardeners, they’re often called scouring rushes and they come by the name honestly. If you pinch their hollow stems between your fingers, you’ll feel a rough crunch reminiscent of sandpaper. What you’re feeling is silica, embedded in the cell walls, giving what otherwise would be a limp noodle of a plant its structure.
The spindly little stalks that we see today are the remnants of what was a much more diverse and impressive group of organisms that once dominated the forests of the late Paleozoic. If we could go back 300 million years to the Carboniferous period, we would have found ourselves walking among forests of horsetails, picking our way between trunks up to a metre thick and over 40 m tall!
For a couple hundred million years, these plants ruled the forested habitats, offering perches for species like pterosaurs and eventually Archaeopteryx. Then, in a form of evolutionary downsizing, horsetails eventually relinquished their foothold to other plants that were better-suited to the changing conditions. Like everything, forests evolved and horsetails got smaller and smaller until they all but disappeared into the understory, just another shape in the mess of green at our feet.
Still, horsetails are worth taking a closer look at. Often reviled as a weed, scouring rushes have proven useful to a number of cultures around the world. First nations used them like sandpaper to sharpen and hone everything from bone and shells used for knife points to pewter and wood. Europeans used them for scrubbing floors and campers today still sometimes use them as nature’s brillo pad. Woodwind players may have used them to shape their reeds. So while they may no longer be the rulers of the forest, these living fossils have shown that it’s adaptability, not size that matters when it comes to longevity.
The Naturalist's Miscellany 