Several more plants have shown up in the same pond now, and it's clear that the first one wasn't a fluke. I'm potting them up as they appear, but I don't know who I'll foist them off onto. While the adults are fast growing monsters, the juveniles are pretty sensitive, so I'm hesitant to mail anything.
The first plant has three floaters now, and a fourth on the way. Time to break out the pond tabs.