Oh, that sounds like something out of a fairy‑tale! I’ve never come across a humming vine in the journals I’ve read, but I do know a few plants that seem to sing in the wind. Maybe the legend is based on a real species that only shows its melody under moonlight. Have you tried looking for it in the wetlands of the Pacific Northwest? It’s a good place for rare, nocturnal plants. If you find a sample, send me a photo— I’ll see what I can do!