Horsetail in two forms - with its whorled branches on the left and center, as single stalks to the right. Photo taken June 5 at U-M Arboretum. This is related to a plant about 300 million years old.

Linda Diane Feldt | Contributor

I played with this plant when I was a kid. I would take it apart, and then put it back together. I’d feel the texture, and was captivated by one of its common names, scouring rush. I would try and imagine living primitively and using this plant to wash dishes by a stream. I tried it a few times; it was surprisingly effective!

Horsetail, Equisetum, scouring rush - by any name it is startling yet common. It grows by rivers and lakes, in moist rich soil. It is called an invasive, but it is hardly new and seems to deserve to be here just by virtue of longevity.

And this plant deserves a closer look. It is ancient - the only surviving member of the family Equisetaceae, that reproduces by spores rather than seeds, has a vascular structure, and does not use photosynthesis. This plant is similar and directly related to the plants that dominated the forests during the Paleozoic era about 300 million years ago. This plant is our reminder of the strange and radically different world that existed so very long ago.

While vastly smaller than the plants that dominated at that time, it’s amazing that it still exists in much the same form. Apparently some things never do change. Although Equisetum has certainly adapted. There are about 20-30 species (the references don’t agree) and there seem to be 2 in our area, the common Equisetum arvense, and the larger horsetail that might be Equisetum telmatiea. I haven’t seen enough of it to be certain.

In the photo, you can see the two types of stems. The whorled branches are still there for a few of the plants, the stalky stems you’ll see later in the season, without branches, are next to it. The pollen producing part of the plant is at the tip, in what is called a strobilus.

The plants are high in silicon, which increases as the plant grows from spring to fall. While that makes it good for scouring, it is not a good plant to eat or even to use as a tea (infusion) once spring has progressed. While still young, the plant has been used as a diuretic, and The German Commission E Monographs report on its use for edema, and externally for slow healing wounds, with no side effects. It has also been used for building bone and treatment of osteoporosis, when used as an infusion steeped about 20 minutes. The high silica content is thought to be one of the ingredients that helps to either slow bone loss or rebuild bone. There are no studies that I’m aware of that confirm this use, but it has been used in herbal folkloric traditions for many years.

My herbal teacher claimed that it worked for her clients, I've had clients who used it with uncertain results. It is difficult to measure the effect, and hard to know even with improvement if the horsetail is the reason.

Long term use is not recommended, which makes its use for osteoporosis less helpful. The concerns are the diuretic effect, a possible loss of vitamin B1, and as the plant ages the increase in silicon could be harmful to the kidneys as well as just long term use. Most of my reference books say that it is toxic to animals, including horses, and should not be mixed with hay or animal feed. I suspect they are referring to the later plant, not the spring Equisetum. There is a big difference in constituents as it ages.

Even though The German Commission E reports no contraindications or side effects, I would suggest much more caution. Use with the advice of a qualified health practitioner (so that you can be certain you don’t have an existing condition that may be irritated or worsened by the plant), if you purchase the herb make certain it was harvested at the proper time (so use a brand that has herbalists on staff), and do not use it for more than a few months at a time.

I found these websites to be helpful and interesting, and the University of Maryland has a little information about the research, which is not much and also poorly done.

http://www.bio.umass.edu/biology/conn.river/equisetm.html

http://daveingram.ca/2010/04/10/exquisite-equisetum/

http://www.umm.edu/altmed/articles/horsetail-000257.htm

I don’t currently harvest Equisetum, I just enjoy it. If it is a new plant to you, I hope that this small bit of background will help you to appreciate it as well. I’m happy every year as I watch it go through its transformation, and I am glad that we have this small remnant of the forests from so very long ago still growing with us.

Linda Diane Feldt is a local Holistic Health Practitioner, Herbalist, teacher and writer. Her next weed walk is Sunday, June 6, from 1-3 p.m., contact her at lfeldt(at)holisticwisdom.org if you are interested. Next Saturday, June 12, The Huron River Watershed Council is sponsoring a weed walk at Gallup Park, contact them to register. That class is free. You can follow Linda Diane on twitter, or find her website for more information. Linda Diane will be at the Mayor’s Green Fair with samples of herbs, weeds, plants, and with her cookbook for sale Friday, June 11. Stop by and say hi.