Calamagrostis (small reed or reed grass) is a genus in the grass family Poaceae, with about 260 species that occur mainly in temperate regions of the globe. Towards equatorial latitudes, species of Calamagrostis generally occur at higher elevations. These tufted perennials usually have hairless narrow leaves. The ligules are usually blunt. The inflorescence forms a panicle. Some may be reed-like.
The plants may be rhizomatous (underground stems with shoots), stoloniferous (with runners), or caespitose (growing in tufts or clumps).
The bisexual spikelets have a single floret and generally they are purple or purple-brown. The spikelets are clustered into inflorescences, which usually develop in early- to mid-summer on long culms ( = stems). Some Calamagrostis can be very decorative; for example, in North America, Britain and Europe, a hybrid cultivar of Calamagrostis (Calamagrostis x acutiflora 'Karl Foerster') is widely grown as an ornamental grass.
The word "calamagrostis" is derived from the Greek word kalamos (reed) and agrostis (a kind of grass).
Many species of Calamagrostis are morphologically similar, but they generally occur in distinct habitats, and they have unique geographical distributions. Given the subtle distinctions between many closely related taxa, there are several species complexes that could benefit from additional systematic study. Even the generic boundaries of the genus are controversial. For example, species in the genus Deyeuxia, distributed largely in the southern hemisphere are morphologically very similar to species of Calamagrostis. It may be appropriate to recognize all of these species in a single genus, but this will require detailed scientific study of DNA of species from around the world.
- Calamagrostis × acutiflora - feather reedgrass (hybrid Calamagrostis arundinacea × Calamagrostis epigeios)
- Calamagrostis arundinacea - rough small-reed
- Calamagrostis bolanderi - Bolander's reedgrass
- Calamagrostis breweri - shorthair reedgrass
- Calamagrostis cainii - Cain's reedgrass
- Calamagrostis canadensis - Canadian small-reed, bluejoint, bluejoint reedgrass, bluetop, meadow pinegrass, Canadian reedgrass, marsh pinegrass, marsh reedgrass.
- Calamagrostis canadensis var. canadensis (Michx.) Beauv.
- Calamagrostis canadensis var. langsdorfii (Link) Inman bluejoint
- Calamagrostis canadensis var. macouniana (Vasey) Stebbins bluejoint, Macoun's reedgrass
- Calamagrostis canescens - purple small-reed
- Calamagrostis chalybaea
- Calamagrostis coarctata - arctic reedgrass
- Calamagrostis deschampsioides - circumpolar reedgrass
- Calamagrostis epigeios - wood small-reed, bushgrass, reed bent
- Calamagrostis epigeios ssp. macrolepis - Chee reedgrass
- Calamagrostis epigeios ssp. meinshausenii - Meinshausen's reedgrass
- Calamagrostis expansa - Maui reedgrass
- Calamagrostis foliosa - leafy reedgrass
- Calamagrostis hillebrandii - Hillebrand's reedgrass
- Calamagrostis holmii - Holm's reedgrass
- Calamagrostis howellii - Howell's reedgrass
- Calamagrostis hyperborea - northern reedgrass
- Calamagrostis inexpansa
- Calamagrostis koelerioides - fire reedgrass
- Calamagrostis × kolymensis - Kolymen reedgrass
- Calamagrostis lapponica - Lapland reedgrass
- Calamagrostis leonardii
- Calamagrostis montanensis - Plains reedgrass
- Calamagrostis nutkaensis - Pacific reedgrass
- Calamagrostis ophitidis - serpentine reedgrass
- Calamagrostis perplexa - wood reedgrass
- Calamagrostis pickeringii - Pickering's reedgrass
- Calamagrostis porteri - Porter's reedgrass
- Calamagrostis pseudophragmites
- Calamagrostis purpurascens - purple reedgrass
- Calamagrostis purpurascens var. laricina - purple reedgrass
- Calamagrostis purpurascens var. purpurascens - purple reedgrass
- Calamagrostis rubescens - pinegrass, pine reedgrass
- Calamagrostis scopulorum - ditch reedgrass, Jones reedgrass
- Calamagrostis scotica - Scottish Small-reed, a rare species under protection by the UK Biodiversity Action Plan
- Calamagrostis scribneri - a species of questionable taxonomic status, that has been recognized in western North America; according to ITIS, a synonym of Calamagrostis canadensis var. canadensis (Michx.) Beauv.
- Calamagrostis sesquiflora - one-and-a-half flower reedgrass
- Calamagrostis stricta - narrow small-reed, narrowspike reedgrass, slim-stem reed grass, slimstem reedgrass
- Calamagrostis stricta var. borealis - boreal reedgrass
- Calamagrostis stricta var. stricta - slimstem reedgrass
- Calamagrostis tweedyi - Tweedy's reedgrass
- Calamagrostis varia
- Calamagrostis villosa