The Collaborative International Dictionary of English v.0.48:

Blue grass \Blue" grass`\ (Bot.)
   A species of grass (Poa compressa) with bluish green stems,
   valuable in thin gravelly soils; wire grass.
   [1913 Webster]

   Kentucky blue grass, a species of grass (Poa pratensis)
      which has running rootstocks and spreads rapidly. It is
      valuable as a pasture grass, as it endures both winter and
      drought better than other kinds, and is very nutritious.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blue grass
    n 1: any of various grasses of the genus Poa [syn: bluegrass,
         blue grass]

U.S. Gazetteer Places (2000):

Blue Grass, IA -- U.S. city in Iowa
   Population (2000):    1169
   Housing Units (2000): 459
   Land area (2000):     2.693635 sq. miles (6.976483 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    2.693635 sq. miles (6.976483 sq. km)
   FIPS code:            07075
   Located within:       Iowa (IA), FIPS 19
   Location:             41.511915 N, 90.764984 W
   ZIP Codes (1990):     52726
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Blue Grass, IA
    Blue Grass