Did Shakespeare really believe that ferns seeds could make you invisible? I doubt it Credit: Gap Gardens As we all know, Prince Hal turns out well in the end (see Henry V), but one of the themes of Henry IV, Part 1 is that the young prince spends too much time in the taverns of East-cheap with Sir John Falstaff and various other ne’er-do-wells. Hal likes to play tricks on Falstaff, and at one point he arranges for Falstaff to be robbed just for the fun of listening to him recount the exaggerated story. In the middle of this tomfoolery, a villain involved in the robbery comments to his accomplice: “We have the receipt of fern seed; we walk invisible.” A puzzling remark for, as gardeners know, ferns don’t have seeds. Why ferns don’t have seeds is harder to explain – suffice to say that ferns have a complex life cycle that makes no sense until you realise it’s a hangover from the aquatic ancestors of all green plants.