The bioluminescent Firefly Petunia produces a steady, soft glow much like moonlight. It debuted last spring to overwhelming enthusiasm and earned a place on the cover of Time Magazine’s best ...

Still, I’d rushed the petunia into a windowless room. My eyes took a moment to adjust to the darkness. But then I saw it. The white blooms gave off a green luminescence. The glow was indeed faint.

One example is the genetically engineered Firefly bioluminescent petunia, which glows in the dark. Introduced earlier this year by the biotechnology firm Light Bio of Sun Valley, Idaho ...