darnel n. (Bot.) Any grass of the genus Lolium, esp. the Lolium temulentum (bearded darnel), the grains of which have been reputed poisonous. Other species, as Lolium perenne (rye grass or ray grass), and its variety Lolium Italicum (Italian rye grass), are highly esteemed for pasture and for making hay. Note: Under darnel our early herbalists comprehended all kinds of cornfield weeds.
... the detection of a weed in a large wheatfield on his estate in England. In these cases, however, there is no reason to suppose that diligent husbandry has done more than to eradicate the pests of agriculture within a comparatively limited area, and the cockle and the darnel will probably remain to plague the slovenly cultivator as long as the cereal grains continue to bless him. [Footnote: Although it is not known that man has absolutely extirpated any vegetable, the mysterious diseases which have, for the last twenty years, ... — The Earth as Modified by Human Action • George P. Marsh