Hemlock

Heb. rosh (Hos. 10:4; rendered “gall” in Deut. 29:18; 32:32; Ps. 69:21; Jer. 9:15; 23:15; “poison,” Job 20:16; “venom,” Deut. 32:33). “Rosh is the name of some poisonous plant which grows quickly and luxuriantly; of a bitter taste, and therefore coupled with wormwood (Deut. 29:18; Lam. 3:19). Hence it would seem to be not the hemlock cicuta, nor the colocynth or wild gourd, nor lolium darnel, but the poppy so called from its heads” (Gesenius, Lex.).