Sometimes it seems to me that the most interesting and unusual plants found in the world usually end up being what we call “living fossils.” Equisetum — commonly known as horse tail, snake grass or puzzle grass — is one of these.These plants are what you would call “near cosmopolitan,” being absent only from Antarctica. Equisetum is the only living genus of the entire class of Equisetopsida, which was extremely diverse and dominated the understory of the late Paleozoic forests for more than hundreds of millions of years.
Horse tails look like long, thin segmented reeds that grow very close to one another in usually wet, sandy soils. Some species are semiaquatic and others are adapted to wet clay soils.
I like to use the common horse tail, Equisetum arvense, very sparingly in the landscape. It has an unusual ability to regenerate after being chopped down to the ground and spreads very quickly throughout the garden where water is abundant. This is because of the rhizomes, or root structures, that are deep underground and almost impossible to dig out.
I have found that this plant is best suited for use in a confined space with medium to dappled light. Pots, concrete barriers and closed planter areas are definitely the best place for this beautiful architectural plant. Otherwise you will end up with a voracious invader.
On the other side of the coin, this plant, once established in the proper growing conditions, can be very low maintenance. Because it has no leaves to speak of, it is very easy to keep clean.
Designers and architects all love this plant because of its unusual shape and tight growing configuration. The segments of the stalks on these plants are extremely dark and regular and look attractive against the dark green of the stem. It has been suggested that the pattern of spacing of the nodes or segments on the stalks — especially near the tip or apex of the stalk where they become increasingly close together — inspired John Napier to discover logarithms.
I don’t know all about that, but I do know that if you place your equisetum out in the full sun you will see tip burning and yellowing of the stalks. The beauty of this plant is its perfect symmetry.
Many people love to hedge equisetum and shear off the top or apex of the stalk creating a hedge. This will control further upward growth but it often results in brown ugly tips where the reeds have been cut. This will often be exacerbated by hot early and midday sun and I feel it takes away from the beauty we are trying to achieve with this plant.
Typically this plant needs a little bit of maintenance to look its best because the stalks near the plant’s center die back or become too crowded. By grabbing the stalk low near the base, many times you can pull out the dead and dry-looking reeds cleanly leaving the green and attractive stalks to enjoy.
I appreciate this plant with a variety of heights and find that they look their best when they get enough sun and water to be strong and hardened off but not dehydrated or dried-out looking.
If you do plant some equisetum in your yard and it takes off into your garden, it is fairly difficult to eliminate. It is recognized in New Zealand and in the state of Oregon as an “unwanted organism” unaffected and difficult to control by many herbicides designed to kill seed plants. Because the common equisetum arvense prefers acid soil, a good trick for eradication is to use lime in conjunction with other herbicides and raise the soil pH to 7 or 8.
When handling this amazing plant, you will notice that the reeds have an interesting rough texture and outer covering. Upon microscopic inspection, you will find that the stems are coated with abrasive white silicates secreted by the cell structure of the plant. This makes them useful for scouring metal items, pots and cookware.
Rough horsetail E. hyemale is boiled and dried in Japan where it is then used in the final polishing process on woodcraft producing a smoother surface than any sandpaper.