Culms 2-80 cm. Blades 2-11 cm long, 4-9 mm wide, margins ciliate basally. Primary branches to 8 cm, widely spaced, often separated by more than their own length. Spikelets with 4-9 (20) florets, densely clustered, appressed to and concealing the branch axes; lemmas about 3.5 mm. 2n = unknown.
Cladoraphis cyperoides was once collected on a ballast dump at Linnton (near Portland, Oregon). It is not known to have persisted in North America. The spinelike leaves and panicle branches would probably make an encounter memorable.
"decumbent" is not a number.