Nature’s Nail File: The Horsetail Rush!
If ever there was a plant that deserved to be nicknamed “a living fossil,” it would be the horsetail rush. Horsetail rushes are ancient plants dating from the Devonian Period (approximately 400 million years ago). In shape and growth form, they are distinctive. Horsetails, scouring rushes, and members of the genus Equisetum look like no other plants. They are made up of sections of hollow tubes that grow upright, sometimes reaching five or more feet tall. Their leaves are so small that they only form a slight fringe around the nodes. The plants resemble green straws with occasional tan horizontal stripes along their length. Sometimes, a spore-bearing cone grows at the tip of each “straw.”
Have you seen horsetail rushes? They prefer to grow along the edges of creek beds in places that are at least seasonally wet. Rhizomes creep laterally underground, branching occasionally and sending up their green, aerial stems. Although horsetails are prolific in the damp climate of the Pacific Northwest, they can be found almost everywhere in moist micro-climates. The 15 species of Equisetum are nearly cosmopolitan in distribution, absent only in Australia and New Zealand.
Texas has three species. The Common Horsetail, with its whorled branches that could be said to resemble the tail of a horse, is found only in the Texas Panhandle. The two other species are found in streambeds, irrigation ditches, lakes, seepage slopes, and swampy areas across the state. These two, the Scouring-Rush Horsetail and the Smooth Horsetail, hybridize readily. I was surprised to learn that the hybrids are more common than the parent species!
I found the hybrid horsetail, sometimes called Ferriss’ Horsetail, on Medio Creek in Bee County. Unlike the Scouring-Rush, which has a roughened stem surface, the Smooth Horsetail is more or less smooth or slippery. The hybrid has an intermediate roughness.
The roughness of horsetails is due to silica grains forming “wartlike tubercles” on the stems, giving them a sandpaper feel. “Both Native Americans and early settlers, who were familiar with European species, used horsetail stems for cleaning and polishing.” Europeans used them for scouring pots and pans, while the indigenous people used them “to polish pipes, bows, arrows, bone tools, and fingernails.”
Yes! Even a modern botanist, Rebecca Swadek of the BRIT “notes that they make an excellent nail file.” Around the world, horsetails have been used to hone the reeds of woodwind instruments and to polish fine wooden products. A Japanese study (Noguchi et al.1981) showed that “the silica-laden stems are superior to commercial sandpaper in their ability to create higher glosses and smoother surfaces.” Who knew?
Despite its usefulness, the horsetail is a fascinating and unique plant. It is the only plant that requires the element silicon as a nutrient to grow. The silicon compound silica helps the stems stay erect and functions like lignin, which is common in trees but almost absent in horsetails.
The ancestors of horsetails were not only understory plants but immense trees with bases two feet thick and heights of 60 feet or more. They were part of the vast swamp forests that produced modern-day coal deposits and thus constitute a significant source of fossil fuels.
Like mosses and ferns, horsetails reproduce by spores. The little spore cases found on the tips of some stems crack open when ripe and release the spores. Each spore has four ribbon-like appendages that coil and uncoil with changes in humidity. These appendages are unique among vascular plants and aid in spore dispersal. However, horsetails readily reproduce vegetatively from rhizomes, which spread rapidly. In the hybrids, like the one I found on Medio Creek, vegetative reproduction is the only form of reproduction. That hybrid, the Ferriss’ Horsetail, does not make viable spores. Still, the hybrid may be the most common form of Equisetum in Texas due to its “rampant rhizomes.”
I hope you will discover horsetails. Some nurseries carry them if you can’t find them in the wild. Their ancient lineage, unique form, and diverse uses (from cleaning pots to filing your nails!) make them fascinating plants.