Phragmites, the Common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. Phragmites australis is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species. In particular the South Asian Khagra Reed – Phragmites karka – is often treated as a distinct species.

The generally accepted botanical name of Common reed is Phragmites australis (Cav.) Trin. ex Steud.. However, it is still often known as Phragmites communis Trin.; other synonyms include Arundo phragmites L. (the basionym), Phragmites altissimus, P. berlandieri, P. dioicus, P. maximus, P. vulgaris^{[clarification needed]}.

Recent studies have characterised morphological distinctions between the introduced and native stands of Phragmites in North America. The Eurasian phenotype can be distinguished from the North American phenotype by its shorter ligules of up to 0.9 millimetres (0.04 in) as opposed to over 1.0 millimetre (0.04 in), shorter glumes of under 3.2 millimetres (0.13 in) against over 3.2 millimetres (0.13 in) (although there is some overlap in this character), and in culm characteristics.^{[citation needed]}