I did a little more research (5 whole minutes!), and it turns out that the classic Lotus Flower that I always picture in my mind is the Nelumbo Nucifera, which is very pretty but also quite edible! People eat the seeds and root-stalks all the time, and they can even be ground into a type of flour. The flowers are often used in making tea. Nelumbo Nucifera has some other interesting properties such as the ability to suck heavy metals out of the water supply. But it is not a recreational drug at all!
Perhaps my misconception comes from the story of Odysseus landing on the island of the Lotus Eaters. Apparently there is disagreement regarding what plant exactly the Iliad was talking about. It may have been the Nymphaea nouchali var. caerulea, which is actually a water lily and does have some mild narcotic effects. Or perhaps Odysseus ate of the Ziziphus Lotus which is actually a rather ugly fruit-bearing tree related to the jujube. No beautiful flowers here, however.
And then the term "Black Lotus" itself has more references to works of fiction than to any actual plant. So there it is. Argyle continues to wander aimlessly throung the swirling Mists of the Unknowing.
