Don't brush it off: Why horsetail is an important -- and long-lived -- plant
Ready for a blast from the past? Check out equisetum, a plant that hearkens to ancient fern forests some 350 million years ago. Equisetum is a relic of a different time, a different continent, and a different climate -- and it grows right here in new-millennium Kane County.
If the name equisetum doesn't still doesn't ring a bell, you may know these plants by the common name horsetail. Both words often refer to an entire group of plants, as equisetum comprises roughly 20 different species.
Equisetums are coarse-textured, erect plants. They lack flowers but reproduce instead by spores. Horsetails grow in colonies, connected underground by rhizomes -- so if you see one, you'll probably see a bunch. Some are low to the ground, while others can be almost 3 feet high. Many of them have branches emanating from the stem at intervals and encircling the stem. The branching habit suggests a horse's tail -- hence, the common name. The scientific name "equisetum" derives from the Latin equus (horse) and seta (bristle).
The individuals that don't have branches are the fertile plants. They grow straight up-and-down, like pipes. One species goes by the common name, "pipes."
These fertile equisetums have an odd-looking, oval structure at the top. This top section is the cone, from which thousands of spores disperse to make new horsetails.
Most people are familiar with broad-leaved plants -- maple trees, rhubarb, violets, corn, and the like. The leaves are conspicuous and showy, but most importantly, they are food factories. By contrast, equisetum leaves are tiny, insignificant, scale-like structures growing at nodes along the stem. These leaves can't make food, because they lack the factories (chloroplasts). Instead, food production is the job of the stem and branches, where chloroplasts are present. Horsetails are homely, in contrast with all the flowering plants that surround them. The showy flowers of fields and gardens are designed to attract pollinators. Pollination is necessary for the plants to make seeds. Horsetails do not need flowers, because they disperse spores from the cones of fertile individuals.
So horsetails have no pretty flowers, and no leaves to speak of. They are cool plants, however, for what they do have. The stems and branches contain silicates, which are a complex group of minerals that make the surface abrasive. You can feel this if you twirl a stem between your fingers. In the old days, people used horsetails for scouring metal pots and pans -- kind of the precursor to Brillo pads back in the day. (The common name of one species is "scouring rush.") The list of medicinal applications of equisetum is extensive. According to "Ethnobotany of the Forest Potawatomi Indians" by Huron H. Smith, the Potawatomi used infusions of equisetum for kidney trouble, lumbago, and bladder ailments. Kelly Kindscher reported in "Medicinal Wild Plants of the Prairie," that the Cree peoples used horsetail in treatment for specific illnesses. "The Crees made a medicine to correct menstrual irregularities by boiling the horsetail," and "Women drank it after childbirth to 'clear up the system.'" Although equisetum is a folk medicine ingredient, its medicinal value isn't scientifically verified. The adage "Don't try this at home, kids" applies to equisetum and many other wild plants. Note, too, that equisetum is not an edible plant. In addition to silica, it contains a chemical mix of alkaloids, saponins, tannins, and volatile oils. Some of these compounds occur at toxic levels. Cattle grazing in fields with horsetail are often stricken with severe illness and sometimes death.
There are four species of equisetum in Kane County. Common horsetail is, well, common. It grows in habitats that range from wet to dry, shaded to sunny, pristine to disturbed. Its scientific name is equisetum arvense. Arvense means "of the meadow or field."
Scouring rush and short scouring rush also grows in our area. Scouring rush is equisetum hyemale, which is derived from the Latin "hiemalis," of or about winter. As the late naturalist, Dick Young wrote, "the rusty terminal cones … make (scouring rush) a cheerful wintertime accent for home landscaping." Short scouring rush, equisetum laevigatum gets its name from the Latin word "laevigata," meaning smooth or polished. This textual difference is relative, because the short scouring rush is, in fact, abrasive. Both of these species occur in woodlands and meadows.
Lastly, we have pipes, equisetum fluviatile. This species likes wet areas, as its name implies ("fluviatile" means found in or near rivers). It's a beautiful accent to the sedges and wildflowers of a marsh.
Despite the fine features of horsetails, not everyone is a fan. Some equisetum is considered aggressive, both here and abroad. Equisetum arvense is an invasive species in New Zealand, where ecologists there are battling to halt its spread. They have employed the services of an insect from Europe, the horsetail weevil, as a biological control.
Whether you love them or hate them, you have to admire horsetails for their longevity on an ever-changing planet. Some 350 million years is a long time to hang around. Who knows, these living fossils may outlive us all.
• Valerie Blaine is the environmental education manager of the Forest Preserve District of Kane County. You may reach her at firstname.lastname@example.org