This common reed forms large beds in shallow water; it has round, hollow stems, which typically grow to 2m in height, but may reach 4m (2). These stems grow from a system of stout, creeping rhizomes (3). The flat leaves taper into a point, and are attached to the stem by smooth sheaths, which are loose so that the leaves all point in one direction in the wind (2). The flowers are borne on highly branching purple inflorescences, which measure from 20 to 60cm in length (2). The flowers are grouped into 'spikelets', which are 10-15 mm in length and support 1-6 flowers (2).