Equisetum scirpoides is a small, rhizomatous, unbranched member of the horsetail family (Equisetaceae) that is easily overlooked due to its small stature. Equisetum scirpoides occurs widely in lowland bogs and forests, all the way to subalpine meadows, and alpine tundra. Equisetum scirpoides is one of the easiest of the horsetails to identify since it is evergreen (most others in the genus are deciduous) and has a characteristic low-growing, very wiry appearance. This species is unbranched, low-statured, and has small cones at the tips of its stems. Both sterile and fertile stems look alike in E. scirpoides, and the thin, kinked and curvy stems lack a central cavity. The stems grow from a slender brown rhizome, may grow up to 15 cm long and are 1.5 mm thick. The cones are black, up to 3 mm long and pointed at the tip. It most similar to E. variegatum which is also evergreen and unbranched, but E. variegatum has a central cavity in the stem, is taller (up to 50 cm), and thicker (up to 3 mm).
The cones of Equisetum scirpoides mature and shed spores in late summer or can remain unopened until the following the spring.
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.
Refer to Equisetum arvense for the known uses of horsetails and scouring rushes in general. The Haisla Indians of British Columbia reported that E. scirpoides was eaten by grizzly bears (Moerman 1998).
Equisetum scirpoides is a widespread circumpolar species. Outside of Alaska E. scirpoides occurs in northern Eurasia. In North America E. scirpoides occurs in Greenland, in all of the Canadian Provinces, south to northern Washington state, Idaho, and Montana in the western U.S., to South Dakota, Iowa, Illinois, Michigan, Wisconsin and Minnesota in the central U.S., and in New England in the East. E. scirpoides occurs in most of Alaska, except for southern coastal regions. This species occurs on the north side of the Alaska Range in Denali, in the upper Yentna River drainage in the southwest part of the park and east of the upper Chulitna River drainage in the Cook Inlet basin region of the park.
Throughout its North American range, Equisetum scirpoides occurs at altitudes of 0-1000 m where it is considered a montane to alpine species. It occurs at 122-1533 m in Denali, at an average of 800 m, and with most occurrences at 800-1100 m elevation. E. scirpoides occurs more frequently on slopes greater than five degrees when compared to the other species in the genus in the park (approximately 28% were on north-facing slopes, 23% on south-facing slopes and 49% on slopes less than five degrees). Most of the occurrences with slopes greater than five degrees were on mild to moderate inclines (~8-23 degrees) and this is similar for both aspect classes. E. scirpoides increased in frequency from 300 m to 1100 m, occurring in ~25% of measured plots in the 900-1100 m elevation class, and occurs in ~20% of measured plots at elevations greater than 1100 m. It had the highest frequency of all species in the genus at elevations 900-1100 m and over 1100 m.