Cinna is a small genus of perennial grasses in the family Poaceae (order Poales), commonly known as woodreeds. The genus contains only four recognised species, yet collectively they span a wide range across the Americas and northern Eurasia, making the group notable for its broad distribution relative to its modest diversity.
Woodreeds are slender, shade-tolerant grasses that produce long, soft, drooping panicle inflorescences. They are characteristic plants of moist, sheltered habitats — streambanks, woodland edges, and areas near standing or flowing water. The genus is placed within the large grass family alongside many of the world's most economically important cereals and turf grasses, though Cinna itself is a minor genus with no significant agronomic use.
The four species divide broadly by geography: Cinna arundinacea (sweet woodreed or stout woodreed) is native to eastern Canada and the eastern and central United States; Cinna latifolia (drooping woodreed) has the widest range, extending from Norway eastward across northern Eurasia to Japan and across Canada including Arctic territories into the northern and western United States; Cinna bolanderi (Bolander's woodreed) is a narrow endemic of a handful of counties in central California; and Cinna poiformis occurs from Mexico and Central America south through Venezuela, Colombia, Ecuador, Peru, and Bolivia. Several species once placed in Cinna have been reassigned to other genera including Agrostis, Calamagrostis, Muhlenbergia, and Sporobolus.
Distribution
Cinna species occur across the Americas and northern Eurasia in moist, often riparian habitats. C. latifolia has the broadest range, spanning Norway to Japan and across boreal North America; C. arundinacea is restricted to eastern North America; C. bolanderi is a narrow Californian endemic; and C. poiformis ranges from Mexico to the Andes.
Ecology
Woodreeds grow in moist areas, particularly near bodies of water such as streams and lake margins, and in shaded woodland settings. Their preference for wet, often disturbed riparian zones means they are frequently found along streambanks and forest understory habitats in temperate and boreal regions.
Taxonomy Notes
Several species historically assigned to Cinna have been transferred to other genera, including Agrostis, Andropogon, Arctagrostis, Calamagrostis, Dichelachne, Echinopogon, Limnodea, Muhlenbergia, Pogonatherum, and Sporobolus. The genus currently holds four accepted species.
