A perennial herb from slender rhizomes. The stems are 1-3 m. in height, cylindrical, light green, with a few sheathing vestigial leaves at the base. Spikelets number several to many, and are 5-10 mm. long and oval. A specialized leaf that appears to be a continuation of the stem exceeds the spikelets.
Scales are shiny orange to brown, often with a conspicuous green midrib.
The scales are slightly greater in length than the nutlet itself. In flower from June to September. Softstem bulrush is a persistent emergent found in deep and shallow marshes, lakes, streams, and occasionally bogs. It may form large stands or be intermixed with other emergent species. Softstem bulrush usually prefers mucky substrates with more stagnant conditions than those preferred by hardstem bulrush.