Really nice link! ^_^Anacharis sounds familiar!
So if that's what it is, it can't be collected.
There is some good info about collecting native and non-native plants here. Brazilian elodea is a do not collect. https://fortress.wa.gov/ecy/publications/documents/0603004.pdf
Yeah it was especially sold to people with goldfish tanks because they love to munch on them.Anacharis sounds familiar!
So if that's what it is, it can't be collected.
There is some good info about collecting native and non-native plants here. Brazilian elodea is a do not collect. https://fortress.wa.gov/ecy/publications/documents/0603004.pdf