Source : Webster's Revised Unabridged Dictionary (1913)

Redtop \Red"top`\ (-t?p`), n. (Bot.)
   A kind of grass ({Agrostis vulgaris}) highly valued in the
   United States for pasturage and hay for cattle; -- called
   also {English grass}, and in some localities {herd's grass}.
   See Illustration in Appendix. The tall redtop is {Triodia
   seslerioides}.