Equisetaceae

Horsetail Family

Horsetails

FAMILY: Horsetail family (Equisetaceae) – Equisetum genus.

SPECIES: #1 field horsetail, common horsetail, scouring rush, or penny shiners (Equisetum arvense L.). #2 tall or western horsetail (Equisetum hyemale L.). #3 smooth horsetail (Equisetum laevigatum A. Braun).

TO UTILIZE AS FOOD: The young shoots of all Equisetum species are edible in small amounts after cooking (Tilford p. 76). They’re not a safe wild food when eaten fresh. Only shoots less than a few centimeters tall have pulp. After that point, they become tough, hollow, and essentially worthless as food. Rhizomes of all species listed above are also edible. Horsetails contain several harmful compounds including: enzymes (thiaminase), alkaloids (equisetin, palustrine, and nicotine), saponins (equisetonin), and organic acids (malic, acontic, and oxalic). Thiaminase is the main toxin in horsetails. It destroys vitamin B1 (thiamine) and causes a deficiency disease called beriberi. Cooking destroys thiaminase (Deshpande p. 372), but other antinutritive compounds may endure the process.

Field horsetail (E. arvense) produces two types of stems: #1) Fertile stems emerging very early in spring tipped by spore-bearing cones; and #2) Infertile stems that are branched at the nodes. Fertile stems are light brown and have the aroma of “rodents nesting in a barn.” Although unrelated to alfalfa, the aroma is similar, except for horsetail’s additional musty and pond-like components. Fertile stems are tender and juicy when they first emerge. Outer skins easily peel away to reveal the inner pulp. Peeling the skins is unnecessary, but removing the spore clusters atop the stems may be wise. Despite the unusual aroma of fresh horsetails, the cooked flavor is very good. After brief boiling, the texture is tender, chewable, and genuinely spaghetti-like. Musty, alfalfa-like, and pond-like components dissipate, leaving only starchy pleasantness to enjoy. The resulting broth is clear yellow and equally appealing. Stems can be dried and ground into mineral-rich flour. Gathering a supply of horsetail stems is easy, making these plants a valuable resource to foragers in early spring.

NOTES: All the western horsetail (E. hyemale) and smooth horsetail (E. laevigatum) samples were gathered too late, long after these straw-like plants became tough. Gathering horsetails early is imperative. They arise soon after the snow melts, or even before the snow melts. Several opportunities to try field horsetail (E. arvense) also passed by, but thanks to the effects of elevation that permit a type of “seasonal time travel,” I found some colonies at higher elevations later in the season. The growing season starts early at low elevations and late at high elevations, so ascending a mountain takes a forager a few steps back in the growing season. Even though the colonies of field horsetail I found at lower elevations were mature in June, colonies on Granddaddy Mountain in northern Utah were just beginning to grow. This temporal-like effect of elevation is very helpful to southwestern foragers, or any foragers in mountainous terrain. If a wild food isn’t quite ready, decrease elevation. If a wild food is past its prime, increase elevation. Elevation extends the gathering season.

Horsetails contain large amounts of silicon in various forms. About 25-29% of the Earth’s crust is silicon, making it the second most abundant element in the crust. It typically occurs as silicon dioxide (SiO2), which is also called silica and more commonly known as sand or quartz. In plants, silicon is usually absorbed in the form of orthosilicic acid (H4SiO4). After absorption, plants may convert it to silica or other forms. Pure silica is a white powder that’s commonly added to foods as an anticaking agent. Its presence in horsetails is not a concern to foragers. It’s neither harmful nor helpful. It merely passes through the body via one route or another. Silicon has not been proven to be essential for human health, but it apparently supports the development of healthy connective tissues.

IDENTIFICATION: The horsetail order consists of one family with one genus and 25 species worldwide. The United States has 16 species, of which 3 are found in the Southwest, Great Basin, and southern Rocky Mountains. Horsetails are distinctive and easy to recognize. They reproduce by spores, rather than seeds, created in delicate cone-like structures at the stem tips. Flowers are replaced by more primitive structures called “sporangia” containing all the parts necessary for reproduction.

Description of field horsetail (Equisetum arvense): FORM upright, perennial plant about 10-70 cm tall emerging from rhizomes; STEMS of 2 types: #1 fertile, fleshy, light brown, delicate, unbranched stems about 10-30 cm tall; and #2 sterile, hollow, green, vertically 7-15 ridged, well-branched stems about 10-70 cm tall that superficially resemble a horse’s tail; LEAVES simple; whorled; blades scale-like, united, and forming sheaths at the stem nodes; FLOWERS absent; SPORANGIA borne on the inner surfaces of peltate scales (sporophylls) clustered in terminal cones on fertile stems; the cones with rounded tips; maturing from early spring to early summer; FRUITS absent; SEEDS absent; SPORES spherical; HABITAT wetlands, especially river banks, nearly worldwide. 

Description of western horsetail (Equisetum hyemale): FORM upright, perennial plant about 40-150 cm tall emerging from rhizomes; STEMS of 1 kind: green, fertile, jointed, hollow, rough, unbranched, vertically 20-40 ridged, and persisting for several years; LEAVES simple; whorled; blades scale-like, united, and forming sheaths at the stem nodes; sheaths about equally broad as long and usually with 2 dark bands; FLOWERS absent; SPORANGIA borne on the inner surfaces of peltate scales (sporophylls) clustered in terminal cones with pointed tips; maturing from spring to summer; FRUITS absent; SEEDS absent; SPORES spherical; HABITAT wetlands, especially river banks in the mountains; temperate and boreal regions nearly throughout the northern hemisphere.

Description of smooth horsetail (Equisetum laevigatum): FORM upright, perennial plant about 20-90 cm tall emerging from rhizomes; STEMS of 1 kind: green, fertile, jointed, hollow, smooth, unbranched, vertically 15-30 ridged, and lasting only 1 year; LEAVES simple; whorled; blades scale-like, united, and forming sheaths at the stem nodes; sheaths longer than broad and usually with 1 dark band at the tips; FLOWERS absent; SPORANGIA borne on the inner surfaces of peltate scales (sporophylls) clustered in terminal cones with rounded to weakly pointed tips; maturing from spring to early summer; FRUITS absent; SEEDS absent; SPORES spherical; HABITAT wetlands, especially river banks, nearly throughout central and western North America.

REFERENCES: Tilford (p. 76) states that the young shoots of all Equisetum species are edible in small amounts after boiling. #1 field horsetail (Equisetum arvense): roots Tilford (p. 76); young shoots Couplan (pp. 16-17) and Kelso (pp. 159-160); young heads (cones) Mars (2009). #2 western horsetail (Equisetum hyemale): rootstocks Moerman (p. 109); young shoots Couplan (pp. 16-17). #3 smooth horsetail (Equisetum laevigatum): rootstocks Moerman (p. 109); young shoots Couplan (pp. 16-17).