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From all I've heard, a heavy snake like a bp will pretty much trample over live plants and kill them. But I suppose if you had a big enough enclosure, and found the right plants and configuration, it could work. I imagine it would take a great deal of upkeep though. Marla posted a link to a similar question that listed toxic and non-toxic plants. If I find it, I'll repost it here for you. (If someone doesn't beat me to it. )

You might want to try a combination of things...like a nice waterfall with some fake plants.