Last season was a strange one in my garden, notable not only for the unseasonably cool and wet weather—the talk of gardeners all over New England—but also for its climate of paranoia. One flower was the cause: a tall, breathtaking poppy, with silky scarlet petals and a black heart, the growing of which, I discovered rather too late, is a felony under state and federal law. Actually, it’s not quite as simple as that. My poppies were, or became, felonious; another gardener’s might or might not be. The legality of growing opium poppies (whose seeds are sold under many names, including the breadseed poppy, Papaver paeoniflorum, and, most significantly, Papaver somniferum) is a tangled issue, turning on questions of nomenclature and epistemology that it took me the better part of the summer to sort out. But before I try to explain, let me offer a friendly warning to any gardeners who might wish to continue growing this spectacular annual: the less you know about it, the better off you are, in legal if not horticultural terms. Because whether or not the opium poppies in your garden are illicit depends not on what you do, or even intend to do, with them but very simply on what you know about them. Hence my warning: if you have any desire to grow opium poppies, you would be wise to stop reading right now.