Alexander Dyce, A General Glossary to Shakespeare's Works

darnel HENRY V., v. 2. 45; 1 HENRY VI., iii. 2. 44; KING LEAR, iv. 4. 5. This weed, “darnel (lolium temulentum), annual darnel or ray grass, grows in fields, has a tall stout stem with rough leaves, flowers in July or August,” Beisly's Shakspere's Garden, etc., p. 113. On the second of the passages referred to in this article Steevens has the following note:“‘Darnel (says Gerard) hurteth the eyes, and maketh them dim, if it happen either in corne for breade, or drinke.’ Hence the old proverb—Lolio victitare, applied to such as were dim-sighted. . . . Pucelle means to intimate, that the corn she carried with her, had produced the same effect on the guards of Rouen; otherwise they would have seen through her disguise, and defeated her stratagem.”