EQUISETOS: CHARACTERISTICS, HABITAT, SPECIES, CULTIVATION, USES - BIOLOGY - 2025

The horsetails (Equisetaceae) are a primitive monotypic family of herbaceous plants, perennials and perennial with rhizomes and stem articulated. The genus Equisetum is the only representative of this family that has survived from the Carboniferous period of the Paleozoic era.

Representatives of the genus Equisetum are characterized by the presence of an articulated rhizome from which hollow aerial stems are formed. These stems present longitudinal striations and are also articulated in differentiated nodes and internodes. In turn, they have laterally whorled branches.

Equisetáceas. Source: pixabay.com

The microphils or reduced leaves are arranged around the nodes forming a small sheath with a toothed crown. Equisettes reproduce from spores that are stored in sporangia grouped in strobiliform structures. These structures are arranged in the terminal position.

On the other hand, they are widely distributed in the northern hemisphere, their presence being greater in temperate zones than in the tropics. They are generally located on terrestrial and aquatic environments, colonizing various deforested or intervened areas, on the edge of water courses or flooded lands.

Commonly known as horsetail or silver cleaner, they are used to polish wood or metals due to their high content of silica. In addition, it has various active principles that provide medicinal properties, in the same way they are used as ornamental plants.

General characteristics

Appearance

Horsetails are vascular plants that fulfill a haplodiplonte life cycle, that is, they live a multicellular haploid phase followed by a multicellular diploid phase. In fact, a manifest alternation of generations is observed: independent sporophytes and gametophytes with spores as dispersal and resistance units.

The gametophytes represent the thallus or structure without organization, and the sporophytes constitute the corm represented by roots, stem and vascular system. These characteristics have made it possible to classify horsetails within the group of pteridophytes.

Stem detail. Source: pixabay.com

Rhizomes

Rhizomes are dense and fairly extensive structures that contribute to their propagation. This allows the development of large colonies. In addition, the rhizomes have the ability to penetrate deep into the ground, which has allowed them to survive droughts, fires and physical damage.

From the adventitious roots of the rhizomes emerge aerial stems, small or long depending on the species, as well as tubers that act as reserve organs. The rhizomes branch in a regular and irregular way alternately, each branch being a replica of the original structure.

Stem

The jointed stems have distinct knots and internodes that grow from the underground rhizome and have photosynthetic functions. The surface of the stems is ribbed and has pronounced folds or striations along the internodes.

The stem is often hollow and the cells of the epidermis accumulate enough silica to act as a support or support. This high silica content also functions as a defense system against pests and fungal diseases.

Leaves

The small leaves, called scaly microfilms or reduced euphils, are only 2 cm long and are arranged as sheaths welded around the stem. In fact, they have little photosynthetic capacity and are only supplied by an unbranched vascular duct.

Detail of the leaves or microfila. Source: Stefan.lefnaer

Taxonomy

- Kingdom: Plantae.

- Division: Monilophyta.

- Class: Equisetopsida.

- Subclass: Equisetidae.

- Order: Equisetales.

- Family: Equisetaceae.

Etymology

- Equisetum: The name of the genus, «Equisetum», comes from the Latin: «equus» horse and «seta» mane.

Habitat and distribution

Horsetails are perennial and perennial plants that prefer moist, clay-siliceous soils, including marshes or bogs. They are especially located on wet and boggy soils, on embankments next to trails or roads, or on uncultivated land and meadows.

This group of primitive plants is found throughout the temperate regions of the northern hemisphere. At present, two chemotypes are distinguished based on the presence of particular flavonoids, one in Europe and the other between Asia and North America.

In the Iberian Peninsula it is located in the humid environments of the northern provinces Asturias, Aragón, Cantabria, Catalonia, Galicia and Navarra. The largest producers and importers of these species are located in Albania, Bosnia-Herzegovina, Croatia, Slovenia, Hungary, Poland, Serbia and Russia

Representative species

Equisetum bogotense

Known as horsetail or silver cleaner, it is a perennial species with jointed stems that can reach 20-60 cm in height. It is located in humid lands between 1,000 and 3,000 meters above sea level throughout Panama, Colombia, Ecuador, Peru, Bolivia, Venezuela, Brazil, Uruguay, Paraguay, Argentina and Chile.

Equisetum bogotense. Source: Penarc

Its brownish rhizomatous stems have a high content of silica, glabrous excretions and membranous segments. The branches have four prominent ridges with differentiated canaliculi and nodal sheaths. It is usually used as a diuretic.

Equisetum arvense

Perennial shrubby species with sterile or fertile rhizomatous stems. The most succulent fertile ones are half as long as the sterile ones. The sterile ones of the bush type are between 5 and 50 cm long and have 20 segments.

Equisetum arvense. Source: MPF

Native to the northern European hemisphere, they are located in environments with a certain humidity, generally near sources or water currents. It is used in arbolaria for the treatment of hemorrhoids and blood vomiting and also to alleviate kidney, biliary, stone and grit diseases.

Equisetum giganteum

The yerba del platero, silver cleaner or horsetail, is a botanical species native to South and Central America. It is characterized by its large size (2-5 m in height and 1-2 cm in diameter) and because it does not differentiate between sterile and fertile stems.

Equisetum giganteum. Source: Frank Vincentz

It has elongated rhizomes and modified leaves in cylindrical pods that are born perpendicular from the nodes of the stem. Used as an ornamental, it is mainly used as a medicinal plant due to its astringent, diuretic, healing and hemostatic action.

Equisetum hyemale

Rhizomatous shrub with a high silicon content, used since ancient times as a raw material for polishing metals. Known as winter shale, it is a species with shrub habits that is found in North America, Central America, Europe and Asia.

Equisetum hyemale. Source: KENPEI

It is characterized by its hollow and articulated stem, similar to a reed, 90 cm high and dark green in color. It has a medicinal use for the treatment of urinary tract disorders, as well as for gastritis, ulcers and intestinal inflammations.

Equisetum palustre

The plant called short beards, horsetail, hundred-knuckles, horsetail or pinillo is a natural horsetail from the Eurosiberian region. It is a 60 cm tall shrub with marked ribs, widely branched, with longer than wide pods.

Equisetum palustre. Source: Mars 2002

It is located on the margin of watercourses or streams, mainly on humid soils, in association with other species such as Populus alba, Equisetum ramosissimum or Saccharum ravennae. It contains certain alkaloids that, ingested by some herbivores, such as horses, can cause motor distortions that would be fatal.

Culture

Through a process similar to ferns, schists reproduce by means of spores or division of rhizomes. Indeed, these species are easy to propagate in humid and boggy areas, on low fertility soils and in semi-shady conditions.

In wild conditions, it is a plant that tends to spread quickly, so it requires enough space to achieve a wide dispersal. As a commercial crop, it can be sown in containers that limit its growth and development to the requirements of the grower.

- Spread

The main technique used commercially to obtain new horsetail plants is through the use of pieces of rhizomes. Its selection is made from healthy and vigorous plants grown as mother plants at the nursery level.

The rhizomes of 10-12 cm in length are planted in the humid substrate 5-6 cm deep. Once the new seedlings are established, they can withstand short periods of dry environment.

The stems develop rapidly forming a dense wall if it grows in full sun exposure. Grown in pots, it develops like a low hedge whose growth can be controlled by maintenance pruning.

When dispersal is not a problem, it can be sown in a humid environment at the edge of a pond or stream. In frost-free climates, horsetails are evergreen, while otherwise the leaves turn brown during winter.

Equisetum arvense sporangia. Source: F. Lamiot

Horsetails develop a dense root system that requires a wide and deep hole when transplanting to the final ground. Once transplanted, it is covered with enough soil, it is gently pressed and the soil is kept moist until its full development.

- Requirements

These species adapt to a wide range of soils, and can also be found in various environments, from swamps or swamps to flood plains. However, they do not tolerate total waterlogging and prefer moist sandy loam soils when planted in containers.

Location

Equisetum best expresses its growth and development in an area with good sunlight, either in full exposure or in partial shade. Also, despite not having invasive roots, it is recommended to plant it away from pipes or artificial drains.

Humidity

Depending on the climatic conditions, it is necessary to water daily, especially if the environment is warm and dry. In the case of containers, it is recommended to keep a support plate that preserves the humidity of the pot.

Fertilization

Horsetails are easily developed plants that do not require frequent fertilization, which would favor their invasive potential. However, under potted conditions or in water gardens, organic compost applications would benefit its development.

Pruning

Maintenance or sanitation pruning work is truly unnecessary to prevent the proper development of the plant or to prevent it from expanding. The rhizome is the structure that controls growth, so removing any part has no effect on its development.

Applications

Medicinal

Horsetails are one of the most used plants in traditional medicine due to the presence of active elements that provide therapeutic and healing properties. For example, ingredients such as salicylic acid, present in leaves and stems, act on the bone system and connective tissue.

The species E. arvense contains numerous mineral compounds such as silicon, in the form of silica, which favors the remineralization of bones. In addition, the presence of flavonoids and saponins exerts a diuretic action on the urinary system, facilitating the elimination of toxins.

Illustration of Equisetum arvense. Source: Carl Axel Magnus Lindman

Its consumption accelerates blood clotting, which affects the healing of ulcers and internal or external wounds. On the other hand, it allows to regulate blood flow and excessive blood levels during menstruation.

Its use has led to good results as an anti-inflammatory, antimicrobial and antifungal. For this reason it is effective in relieving different infections.

Cosmetics

Horsetails contribute to the health of skin and hair, since the presence of silica stimulates the production of collagen. Indeed, collagen is a vital element in preserving the freshness of the skin, as well as the hardness and shine of the hair.

Industrial

Due to its high silica content, various species of the genus Equisetum are used industrially to polish wood and metals. In fact, the ashes have a high abrasive power that facilitates the work of polishing metal or wooden articles.

References

1. Cabezudo Artero, B. and Trigo Pérez, M. (2013) Pteridophytes (Ferns and Allied Plants) Chapter 10. University of Malaga.
2. Equisoceae. (2019). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
3. Ferriol Molina, M., & López Del Rincón, C. (2018). The horsetails. Vegetative characters. Polytechnic University of Valencia. Agroforestry Ecosystems Department.
4. Gallardo-Pérez, JC, Esparza-Aguilar, MDL, & Gómez-Campos, A. (2006). Ethnobotanical importance of a vascular seedless plant in Mexico: Equisetum. Polybotany, (21), 61-74.
5. Equisoceae (2019) Asturnatura. Recovered at: asturnatura.com
6. Prada, C. (1986). Equisetum L. Flora ibérica, 1, 21-29.
7. Ramírez Trejo, R., Pérez-García, B. & Mendoza, A. (2001) The horsetails, plants of the past in the present. Structural Botany and Plant Systematics Area. Biology department. UAM-I. ContactS 40, 33-36.
8. Villas del Fresno, AM & Iglesias Peinado, I. (2006) Equiseto. Professional Pharmacy. Vol. 20. No. 2. Pages 74-77.