There is a rare flower- a blue double-bloomed poppy- that grows on the eastern slopes. (Batman Begins)

Yeah, but not only there. It also grows in Planten un Blomen in Hamburg where i shot the photo. I was totally fascinated by the deep and dark blue color of the flower, not knowing anything about it’s heavy symbol character. But the Blaue Blume is a central, recurring symbol in German Romanticism and stand for desire, love, and the metaphysical striving for the infinite and unreachable.
The name of the blue flowers in A /S/canner /D/arkly by Philip K. Dick is Mors ontologica, which translates loosely as “the being of death itself”. Derived from them is an organic substance called /S/ubstance /D/, which the characters refer to as Slow Death, Substance Death, or simply D. The flowers are grown on large plantations, hidden between rows of corn as cover. Ironically, the drug is harvested by the brainwashed inmates of Substance D drug rehabilitation centers who are suffering from neurocognitive deficits as a result of their drug addiction:

“What does a scanner see? I mean, really see? Into the head? Down into the heart? Does a passive infrared scanner … see into me — into us — clearly or darkly? I hope it does see clearly, because I can’t any longer these days see into myself. I see only murk. Murk outside; murk inside. I hope, for everyone’s sake, the scanners do better. Because if the scanner sees only darkly, the way I myself do, then we are cursed, cursed again and like we have been continually, and we’ll wind up dead this way, knowing very little and getting that little fragment wrong too.”

and another bit by Mark Frost & David Lynch:

DESMOND
Gordon said you were good. The tailored dress is our code for drugs. Did you notice what was pinned to it?

STANLEY
A blue rose.

DESMOND
Very good, but I can’t tell you about that.

(Twin Peaks: Fire Walk With Me)