A question was just posed as to whether Neppies seedlings here in Guatemala might "escape" and naturalize under local conditions. Since we have a prolonged and marked dry season (Nov-April) this seems unlikely, given most of these plants require fairly mesic conditions, year-round.
I do, however, generate phenomenal amounts of fortuitous hybrid seedlings in any perma-wet environment in the rear garden - Heliamphora and Cephalotus pots, in particular seem to be magnets for wind-dispersed seed. A major problem here is preventing female plants being tagged with unwanted pollen when intent on creating a specific cross. I have also been faced with the rather ironic task of having to "weed" up to 12 pitchering adolescent hybrid plants from the pots of near-smothered highland spp.
Here follows two recent pics of "Nepenthes as weeds" - pots are ca. 15 cm diameter.
P'rhaps, something that you don't see too often in cultivation.