Carex capillaris

Aiken et al. (2007) recognize two subspecies. In contrast Kartesz (1994, 1999) and FNA (2002, vol. 23) do not recognize distinct infraspecific taxa in Carex capillaris, FNA (2002, vol. 23) notes, "Carex capillaris is somewhat variable and is often divided into two infraspecific taxa.... When recognized, the southern plants are called subsp. capillaris (C. chlorostachya Steven, C. capillaris var. major Drejer ex Blytt), and the northern plants are called subsp. fuscidula (V. I. Kreczetovicz ex T. V. Egorova) Á. Löve & D. Löve."

Carex capillaris is a wide-ranging perennial graminoid in a variety of habitat types. It has a circumboreal distribution, occurring in North America from Alaska, United States and throughout Canada south in the western United States to California east to New Mexico and South Dakota, and in the eastern United States to New York and Michigan west to Minnesota; it also occurs in Eurasia. There are estimated to be thousands of occurrences worldwide, which face threats from development, cattle grazing and trampling, rights-of-way maintenance, logging, hydrological alteration, recreational activities, invasive species, and other threats in some places. Little is known about trends, but with a large range extent and large number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, this species is considered secure.

Carex capillaris has a circumboreal distribution, occurring in North America from Alaska, United States and throughout Canada south in the western United States to California east to New Mexico and South Dakota, and in the eastern United States to New York and Michigan west to Minnesota; it also occurs in Eurasia (FNA 2002). Range extent was estimated to be over 70 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025). See individual entries for distribution details about the subspecific taxa.

By applying a 1 km separation distance to herbarium specimens and photo-based observations documented between 1994 and 2025, it is estimated that there are thousands of occurrences rangewide (GBIF 2025, iNaturalist 2025, RARECAT 2025, SEINet 2025).

Although threats are not widely documented, this species is threatened by development, cattle grazing and trampling, rights-of-way maintenance, logging, hydrological alteration, recreational activities, invasive species, and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2025). However, their overall impact is likely negligible given the species' broad range, large number of occurrences, and affinity for typically abundant habitats, as well as no obvious intrinsic vulnerabilities.