There was a topic on not too long ago asking about Boston Ferns and I had always thought they were dangerous, but after doing a little research I found out that they are not.
Hopefully it is a non-toxic species. I would be careful if you cham is munch'in on the green though. You should be ok (as long as your fern species is safe) but you might replace it with some confirmed safe plants just to be safe.
Give your veiled some lettuce he may have a plant craving, have you ever offered your veiled fruits and veggies before? they really like em..But make sure not to give em any tomatoes, they're toxic to chameleons. Wish i knew which fern it was.
If you take a picture of the fern, you could probably get an identification from someone here. There are a lot of plant pros here. Or at least they seem to know a lot about plants