[2] The only known species is Hainardia cylindrica, known by several common names, including barbgrass,[3] one-glumed hard-grass,[4] and thintail.

It is native to the Mediterranean and to nearby regions from Madeira and the Canary Islands east to Crimea and Iran.

It is also reportedly naturalized in coastal regions in scattered locales in Australia, New Zealand, the United States (CA OR TX LA SC),[5] Baja California, and temperate South America (Brazil, Uruguay, Argentina, Chile).

[1][6] Hainardia cylindrica is an annual grass of salt marshes and estuaries, thriving in saline and alkaline soils in aquatic habitats.

The top few centimeters of the stem is made up of a cylindrical inflorescence with each spikelet embedded into it and dividing it into segments which can break off.