There are many species of spike rush and they are difficult to differentiate. In general they are small plants often confused with grasses or sedges. They can grow completely underwater and appear as a submerged plant or grow emersed in moist soils.
They grow and spread primarily through rhizomes. Stems are unbranched. All spike rushes have small fruiting spikes at the tips of their stems. Shoreline plants look like bright green grass. Often the submerged plants will be pulled out of the bottom sediment and float to the top like grass clippings with a white root.
Emersed plants are controlled effectively if needed. Submerged plants can be difficult.