Jennifer Schultz Nelson
Extension Educator, Horticulture
When we bought our house, one thing that stood out to me while looking over the typical "new subdivision" (horrible soil) yard was that there was a lot of horsetail rush (Equisetum) growing near the pond. I was intrigued by this odd plant-- I remember it was mentioned in my botany class in college. Others who visited those first few weeks groaned in disgust when they saw it, and promised us we'd never eradicate it from our property. I didn't really see the problem then, and still don't. Equisetum is essentially a living fossil, and it grows where little else will.
Plus they are very unique looking. They look like little green stems with brown joints lined up like soldiers along the bank of our pond. Equisetum is a very ancient genus of plants, thought to date back at least to the middle of the Devonian period, over 350 million years ago. The handful of species alive today are all that remains of what used to be an extensive plant genus that populated most of the world.
There are two large groups within the Equisetum genus: the Horsetails, and the Scouring Rushes, which is what I have in my yard. Both prefer marshy, wet areas in the landscape. The difference is that Horsetails have branches, and have a whorled or bushy appearance. The Scouring Rushes are unbranched. Both lack true leaves, and depend on the chlorophyll in their stems to carry out photosynthesis. Their stems are hollow and have distinct nodes that give them a jointed appearance, much like the individual bones in a horse's tail, suggesting where the common name horsetail originated.
Equisetum dates back to a time when primitive, non-seed bearing plants were the dominant plant life. They are related to ferns, and like ferns, reproduce via spores. The spores are released from a cone-like structure on the top of the plant, and later burrow into the soil, where fertilization occurs. The stems we recognize emerge later.
The root system of Equisetum is rhizomatous, meaning that it is technically made up of modified stems. They are quite extensive and can grow very deep into the ground, reportedly up to six feet! This is why everyone groaned and warned us we'd never get rid of the horsetail rush in my yard. If you try and pull it and leave one little bit behind, it will grow into a whole new plant before you know it. They are surprisingly resilient as well. I left a board near our pond last fall, and this spring when I moved it, the grasses were dead and decayed, but the horsetail was still kicking. It was a little yellow and twisted, but within a day straightened out and greened up.
There are several common names circulating for Equisetum, one being Scouring Rush. The cells of the plant contain silica, which gives the plant a rough texture. Scientists believe the silica containing cells are one feature that makes this plant hard to manage in the landscape, since the silica appears to block penetration of many herbicides.
People have exploited this throughout the centuries, using these primitive plants to scrub, or scour, cooking pots, and utensils. Craftsmen have also used them to polish metal, wood and ivory. At one point the English imported Horsetail from Holland to use for polishing metal. Some still call them Dutch Rushes, referring to this old use.
A current use for Equisetum is in contemporary style floral arrangements, with very angular and minimalist composition. The stem of Equisetum is hollow and compartmentalized between the nodes, and it will hold water. A former floral design student let me in on a secret– you can make small holes in the stem of Equisetum, fill the individual stem section with water and insert other cut flowers. The water will stay inside the Equisetum stem and support the inserted flower. Another reason florists like Equisetum is that they tend to dry out in arrangements without decaying, wilting, or otherwise declining, probably due to the high silica content in the plant that stiffens its cell walls to a great extent, preserving its structure.
Equisetum has always been a plant that spreads rapidly, with potential to be invasive in the right environment. The current popularity of water gardening has seen a surge in sales of this plant as an ornamental. This has created a problem in Australia, the only place besides New Zealand that doesn't have native Equisetums. As this vigorous grower escapes into the landscape, it can potentially crowd out other native plants.
Equisetum naturally occurs in every county in Illinois, but it can still be very weedy and undesirable in some situations. If you decide to plant it, it is a good idea to try and keep it contained by use of underground barriers to restrict its growth. The Equisetum in my yard is somewhat naturally restricted because while it grows freely along the pond, any that pokes up through our lawn gets mowed at some point. Although the mowed pieces could potentially start growing new plants, it hasn't been a problem, probably because conditions are too dry on the surface of my lawn.
In the event that it becomes more invasive, I will have to start looking for a florist who can use it, or start using it to scrub my pots and pans. As long as the Equisetum minds its own business and does not threaten a hostile takeover of my yard, I'm happy to let it live next to the pond.