Recently segregated from Schoenoplectus, this includes, in Michigan, all the annual, cespitose species. See Hayasaka (2012) and Shiels & Monfils (2012) for further information.

1. Culms sharply triangular.

S. mucronata

1. Culms terete or obscurely 3-angled.

2. Achene covered with prominent transverse ridges; perianth bristles none.

S. hallii

2. Achene smooth or obscurely pitted; perianth bristles present or absent.

3. Taller shoots with stems (base of plant to inflorescence) (0.7-) 0.75-0.9 times as long as the entire shoot, including the involucral bract; achenes thickly and asymmetrically biconvex (inner face slightly but clearly convex, outer faces forming a clear angle).

S. purshiana

3. Taller shoots with stems 0.4-0.75 (-0.8) times as long as the entire shoot; achenes flattened-planoconvex (inner face essentially flat, the outer faces gently rounded).

S. smithii