The only non-native aroid I've ever found around here (southeast PA and northern DE) is pinellia. I've seen it in 2 places, but since these were in the same stream valley, they should probably be considered as one. It was not widespread, and certainly did not appear to be invading a large area. Perhaps that's because the really invasive pachysandra which had already covered the area kept it under control.

George

Arum italicum. I think it's on our Noxious Weed List here in Oregon (I'm in Western OR in Portland). It's almost inpossible to get rid of.

Lemma minor is a weed if you still consider it an aroid.

Something else is nagging the back corner of my mind but I can't joggle it loose right now- and it's 3am, when I usually wake up and DO remember all the things I couldn't for the whole day before :-/

Several Syngonium spp. grow feral around here as well as Taro , the dreaded vareigated Devils Ivy , and a few Philos are naturalized along with the many native aroids that grace our rainforests .

Around here, Colocasia esculenta var. aquaticalis is very invasive in waterways. Some other aroids that have escaped and can be seen growing in moister woods and hammocks include Golden Pothos (Epipremnum aureum), Arrowhead Vine (Syngonium podophyllum) and Giant Elephant Ear (Xanthosoma sagitiifolium)
Eric
Orlando,FL z9b/10a

The most problematic ones we have in Singapore are Epipremnum aureum (they call it the "Money plant" here), Syngonium podophyllum, and Diffenbachia spp/ cultivars as they tend to smother everything that gets in their way. We also have Colocasia esculenta, Xanthosoma spp as well as the occasional Philendendron spp/ cultivars and Typhonium spp, the latter "introduced" by our older chinese folks who use it as herbal medicine.