A single spikelet terminates the flowering stem, which is round in cross-section.

Common spikerush is a native rhizomatous perennial of wet sites and is often mat-forming if not bunched. It is distinguished from other spikerushes by the combination of its lenticular achenes that each bear 2 stigma branches, stems standing well over 15 cm tall, and a perennial rhizomatous habit.

Flickr album https://www.flickr.com/photos/plant_diversity/albums/72157689742366245