Green Bulrush is a tall perennial sedge, growing up to 5 feet high on roundly triangular unbranched smooth upright stems (culms). Not all stems are fertile, non-fertile stems may arch over.

Leaves are 1/3 to almost 1 inch broad (1-2 cm) with a slight "M" shape, smooth on top but rough on the margins. There are 6 to 11 alternate leaves per stem. Veins run parallel with the blade. The leaf sheath can be green in the upper stem or brownish on leaves near the base.

The inflorescence is terminal and contains several spherical heads (umbels) containing numerous spikelets, the largest of the heads will have 17 to 25+ spikelets. The entire plant may have numerous heads. These heads angle out in different directions and under the inflorescence are two or more very conspicuous bracts (modified leaves). These vary in length but one is longer than the inflorescence and their bases are green, sometimes with brown spotting on the blades. The individual umbels may have their own small bracts.

The individual flowers have 3 stamens, and brownish overlapping scales. The achenes produced are up to 1.3 mm long and 0.6 mm wide, and when ripe are a brown color with bristles attached. They are spread by the wind.

Habitat: Green Bulrush is found in sedge meadows, alder thickets and wet meadows. It tolerates standing water. Grows best in full sun, but some shade in hot summer months is good. It grows from rhizomatous fibrous roots that spread and form colonies. Also, as the seeds are viable for up to 40 years, it frequently can colonize a disturbed site such as a site recently dredged or otherwise mitigated. Seeds will self-sow.

Names: The genus Scirpus is the Latin name for the bulrush. The species atrovirens has the base Latin word atro, meaning 'dark' and combined with 'virens' means 'dark green'. The author name for the plant classification, ‘Willd.’ is for Carl Ludwig Willdenow (1765-1812), German botanist, a founder of the study of the geographic distribution of plants. He was director and curator of the Botanic Garden of Berlin.

Comparisons: The bulrush group has many species and there are three close relatives of S. atrovirens in Minnesota that can be confused and occasionally hybridize with it: S. hattorianus, Mosquito or Early Dark Green Bulrush, and S. pallidus, Cloked or Pale Bulrush.