Synonyms for Johnson Grass (same or very similar meaning)
WordNet sense 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):
evergreen millet, means grass, Sorghum halepense, Aleppa grass, Sorghum halapenseFrom the ODE community, based on WordNetadd/edit