Poa pratensis L. Glyceria angustata R. BR.
"The Voyage of the Vega round Asia and Europe, Volume I and Volume II" by A.E. Nordenskieold
Sometimes used to adulterate Poa pratensis.
"Seeds of Michigan Weeds" by W. J. (William James) Beal
Poa pratensis Smooth meadow-grass.
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3" by Various