Nature today | Sidewalk Plant of the Week: Horsetail

Horsetail (Equisetum arvense) is a plant of the horsetail family (Equisetaceae). It is a perennial up to forty centimeters high, stems in spring with light brown stems laden with spikes of spores on top. These are the fertile stems, because spores are part of the reproductive cycle. They sit in boxes under a scale-shaped roof, waiting for the wind to blow on them. If the spores land in a favorable place, the male or female spores grow, from which the male fertilizes the female. Then a new horsetail plant is established. Infertile stems appear after about two weeks. Then the fertile stems wither again. These infertile stems are rough on the outside and hollow on the inside and are easy to separate longitudinally because they have a hinged skeleton. In each transition of two members, the so-called node, there is a set of conjoined scales. Also on the node is a wreath of side branches. These side branches can be seen as the leaves of the plant and are somewhat similar to pine branches. Like the stems, they have a hinged structure.

loan shark

Horsetail also makes many roots that go deep into the ground and also form horizontal branches from which new plants can sprout. This form of asexual reproduction makes this plant notorious as an irresistible herbivore. Horsetail is found in the temperate and cold regions of the Northern Hemisphere. It is a member of the group of plants that dominated the earth before the advent of modern flora, say in the age of dinosaurs. Then the horsetail relatives grew into “trees” tens of meters high, from which the existing coal seams of the Earth are greatly formed. Nodules are formed on the rhizome, which has fine yellowish-brown hairs, which serve as a winter storage for the plant. Thanks to those deep roots, horsetail can absorb minerals from the soil layers that other plants can’t reach and then transfer them to the above-ground plant. As a result, horsetail contains many minerals and silicic acid. The silicon in silicic acid is absorbed by the plant to strengthen cell walls.

Horsetail on the sidewalk



The origin of the name is unclear. The second part of the name, Moss, undoubtedly means “vegetable,” as found in German “Gemüse.” But what does the word “lord” mean? One can think of a large group or an army. However, the Germans help again, because the word “Hare” means the army there. But the Germans themselves called the plant “Schachthalm”, which may indicate that the sections of the plant fit together. Hence the modern name given to the plant: lego plant or double plant. Keep in mind that disintegrating is easy, but putting them back together or building other plants is more difficult.
A number of common names often refer to the plant’s distinctive tail shape: field horsetail, loose tree. The plant is also called “roobol” or “ruigebol,” in reference to its rampant nature, or “unjer,” which means “evil spirit.”
By scientific name Equisetum arvense The word equisetum comes from the Latin words “equus” (horse) and “saeta” (hair, brush). But Setum can also be derived from Setrum (tail). If the origin was really Saita, people might have seen a resemblance to a horse’s coarse mane instead of its tail. Arvense is also of Latin origin, meaning “field” or “field”.

Ponytail in all its glory

Origin and place

Horsetail spreads along roads and among weeds, in sandy fields and in clay soil, as long as there is silicon in the soil. The plant can survive well in environments where other plants would die from pollution. For example, the plant was the first to regain its foothold on the slopes after the eruption of the St. Helena volcano in the United States in 1980. Also in industrial areas with severe pollution or highly compressed soils, the plant is often the first to arrive or the last to disappear. So you can wonder about the original species of this plant, which can grow into giant trees thirty meters high, of which only small species remain. These plant species must have been overgrown in prehistoric times. Although the current forms are still known as usury, they cannot match the violence of their ancestors to seize the entire land, as it seemed in prehistoric times. Apparently, the reproduction of flower plants outperforms the spore approach to equilibrium. And this is understandable, because you do not go very far in the roots and it seems that reproduction with spores without the help of insects is cumbersome.
But horsetail can tolerate very well because it is resistant to all kinds of toxins. New shoots sprout from the nodes every year from the deep roots. If there is any deep enough water, the horsetail will survive for a long time.
With a little imagination, you can see a primeval forest reappear if those pesky flowering plants go extinct. Sounds cute, especially when you think of dinosaurs.


Consumption and use


Young shoots can be cooked like vegetables, but they contain a lot of silicic acid which gives a gritty taste. So it is not very attractive. The lush stems that appear in early spring are soft and tasty. Horsetail needs silicon in the form of silicon oxide for strength. Therefore, the planting site should have some sand from which they can get this mineral. Exactly how this happens is not clear, because sand, the source of silicon, is insoluble and must be transported by the plant. Since silicon is present in the oxide form, i.e. sand, horsetail can be used as a light polishing agent or abrasive agent, for example for polishing tin. This is why the name tenwort is sometimes used for the plant. From another kind of poise, shaving straws, the name says it all, the shanks have so much silicone that the abrasive effect is greater and can be used as a cleaning agent for pans and for making sandpaper, which is what was done in the past.
Since horsetail is able to absorb minerals from deep in the soil and absorb them into the leaves and stems, horsetail can be used as a fertilizer. It is enough to simply sprinkle the stems and leaves on the surface of the soil, but an infusion for spraying can also be made. Therefore, it serves as a remedy against all kinds of fungal diseases.
As early as the first century AD, horsetail was described as a wound-healing, astringent and diuretic. But although horsetail has been used as a medicine for centuries, no scientific evidence has been found. It is a plant that contains many minerals and therefore trace elements that are indispensable to living organisms. Horsetail tea is said to be good for the bladder, lungs and kidneys, but you should let it steep for at least half an hour and you shouldn’t drink too much of it.

chemical aspects

Like all plants, horsetail also contains many active substances. The most notable of these is silicon, which is discussed in more detail here.
Silicic acid Si (OH) 4 and SiO2

So the plant has a high content of silicon in the form of silicic acid, a compound of silicon dioxide and water, and SiO2† Silicon dioxide forms a three-dimensional network of silicon atoms surrounded by oxygen atoms, forming a tetrahedron (tetrahedron). It’s easy to imagine that complex structures can arise, especially when metals like aluminum come into play. Then it becomes silicate. These silicates are an important group of minerals and make up approximately 95 percent of the Earth’s crust. They are found in many varieties, of course we know sand, pebbles and rocks, but most gemstones are also silicate: quartz, agate, amethyst, opal, etc.
Horsetail is able to absorb silicon from sandy soil and deposit a large part of it as a solid in the outer walls of the stems. This transformation into a hard substance, mineralization, gives the plant its strength and protects from wind and rain. This may be why the stems are hollow from the inside, because with a strong wall they do not need any filler. The bike frame is also hollow inside and very durable. But it makes the trunk less flexible and therefore the ponytail is prone to breakage. It is common in the plant world for stems to be hollow. Another species of the equisetum family is the common hornbill, and this species, as the name implies, has a larger cavity on the inside than the horse’s tail. Another well-known example is bamboo, because bamboo stalks are also hollow and we know how strong bamboo sticks are. These can contain up to 70 percent silicon.
A small portion of the silicon in horsetail is bound to sugars, fats, and proteins or is found as free silicic acid in colloidal form. This liquid part can be absorbed when the plant is consumed.
If you look at the edges of the leaves under a magnifying glass, you can notice small crystals. You are actually looking for crystals of gems. If you hit the stem from top to bottom, the plant will feel rough.
Horsetail also contains many other minerals such as lime, potassium, sodium, manganese, iron, sulfur, zinc and magnesium.
In addition to minerals, horsetail contains myrrh, saponins, tannins, organic acids (malic, sorrel, bacterial acids), flavonoid glycosides and a whole group of alkaloids. It will go into more detail on this matter.

Well, that was a lot of reading. Out to the outside: to the old university library, where you can admire the seventy original drawings drawn by members of the Association of Botanical Artists for Stoepplantjesalbum. Horsetail was discovered along the way to pavement plant research.

Text: Piet Rieff, Hortus botanicus Leiden
Photos: Flora van Odmans; Haneke Giles Tinky. KU Lovin Natalie Tyrion Pete Reef

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