Equisetum arvense is a rhizomatous, branched member of the horsetail family (Equisetaceae) found in a wide variety of habitats from gravel bars, shrub thickets, and forests in the lowlands to moist sites in scree, subalpine meadows and alpine tundra. Horsetails have rush like stems with ridges of siliceous tubercles and produce spores in cones. Equisetum arvense grows from dark brown to black, felty rhizomes. It has two types of stems. The fertile stems are unbranched, 10-15 cm tall, lack chlorophyll, are pale brown, fleshy, and appear early in the spring before the sterile stems. The terminal cone has a long peduncle. The sterile stems are variable, they may be upright to 80 cm tall and or prostrate but usually are regularly branched. The branches are triangular in cross section and the first internode of the branches is longer than the closest stem sheath. The branches are ascending and the teeth of the sheaths are lance-attenuate. E. arvense is most similar to E. pratense in Denali, but the branches of the latter are spreading, have deltoid teeth on the sheaths, and the first internode of the branches are the same or shorter than the length of the corresponding stem sheath.
The strobilus of Equisetum arvense is produced on a separate fertile stalk in early spring. The vegetative stalk of this species appears a week or so later after spores and shed and the fertile stalk has withered away.
Equisetum species reproduce sexually and asexually. Sexual reproduction is limited by ecological conditions. hygroscopic spores are produced, but they are short lived and germinate depending on humidity. Once germinated, the gametophyte produced by spores requires a recently exposed substrate to become established. Asexual reproduction is by rhizomatous growth which can be rapid in favorable moist and disturbed habitats. Reproduction also occurs by fragmentation of rhizomes and stems. Clones may spread rapidly, and since usually they are sterile, may establish characters indicating taxonomic differentiation.
Equisetum arvense is a host plant to two beetle species (Hippuriphila modeeri and Grypus equiseti), two fly species (Liriomyza equiseti and L. occipitalis, Dolerus germanicus, a sawfly, and Hydraecia micacea, a macro-moth (Biological Records Centre 2008). Four fungi species are known to attack the dead and dying stems of field horsetail: Ascochyta equiseti, Hymenoscyphus rhodoleucus, Psilachnum inquilinum, and Titaeospora equisiti (Peat et al. 2015).
It is likely that many indigenous people did not distinguish the species of horsetail, thus this information will also apply to the other species of horsetail within the Atlas. Horsetail has been used as a tool, food, dye and medicine. It contains alkaloids, flavonoids, sterols, silicic acid, equisitonin, dimethylsulphone, thiaminase, and aconitic acid. It was used as a medicine by North American indigenous people wherever it occurred. The Dena'ina used the ashes of the burned stems and leaves on sores and heated the root to treat aching teeth. As a food, the first green sprouts were eaten in early spring by the Lower Chinook, the Hesquiat, and the Saanich. The Dena'ina and Eskimos of Alaska ate the tubers and nodules in the spring and called them berries. The Dena'ina recognized horsetails as a favorite food of waterfowl, the Dena'ina names for horsetail meaning 'duck food' and 'goose food'. Other peoples ate the cones boiled or pickled. The mature stems with their high silica content were used as sandpaper to polish wood and metal. See references within Garibaldi 1999 for more information.
Equisetum arvense is a cosmopolitan circumpolar species. Outside of North America this species occurs in Eurasia south to the Himalayas, in central China, Korea and Japan. In North America E. arvense occurs in Greenland, all of Canada and south to Mexico. It occurs throughout Alaska, and is common on both sides of the Alaska Range in Denali. Field horsetail is the most common species in the genus in Denali.
Throughout its North American range, Equisetum arvense is found at altitudes 0-3200 m; in Denali it occurs at 67-1533 m, an average of 631 m, and with most occurrences at 700-1000 m. Occurrences above 1200 m were mostly on south-facing slopes. Most (60%) of the occurrences of E. arvense were on flat terrain (with slopes less than 5 degrees), 24% were on south-facing slopes with inclines up to 39 degrees, and 16% were on north-facing slopes with inclines up to 35 degrees. However, most occurrences greater than 5 degrees were on mild inclines (10-20 degrees).
Equisetum arvense is found in a variety of substrates, soils and moisture types. It is characteristic of disturbed sites, grows on nitrogen-medium soils on water receiving sites, and is frequently dominant in early-seral communities (Klinka et al. 1989). It is found on wet to mesic sandy or disturbed sites with permafrost close to the surface. It is also known from dry, sandy surfaces, in pockets of soil on shattered limestone in the arctic, on streambanks, in shady forests, fields, marshes, pastures, tundra and thickets (Botanical Society of the British Isles 2015).