hair grass

from The Century Dictionary.

• noun One of several species of grass bearing small flowers on slender, hair-like branches, especially Deschampsia (Aira) cæspitosa, D.
• noun (A.) flexuosa, and Agrostis scabra.

from the GNU version of the Collaborative International Dictionary of English.

• (Bot.) A grass with very slender leaves or branches; as the Agrostis scabra, and several species of Aira or Deschampsia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A grass with very slender leaves or branches; as the Agrostis scabra, and several species of Aira or Deschampsia.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun fine-leaved aquatic spike rush; popular as aerator for aquariums