The Collaborative International Dictionary of English v.0.48:

Aleppo grass \Aleppo grass\ (Bot.)
   One of the cultivated forms of Andropogon Halepensis (syn.
   Sorghum Halepense). See Andropogon, below.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Aleppo grass
    n 1: tall perennial grass that spreads by creeping rhizomes and
         is grown for fodder; naturalized in southern United States
         where it is a serious pest on cultivated land [syn:
         Johnson grass, Aleppo grass, means grass, evergreen
         millet, Sorghum halepense]