I had hornwort and anacharis in my outdoor pond in Wisconsin. It could handle pretty cold water, you just don't want to shock it by moving it from a cold pond in fall to a warm tank inside. Put the plants in a bucket inside and let them adjust to room temp for a few days before moving to a heated aquarium.

The hornwort was free-floating, but the anacharis was rooted in pots with the water lilies. I just clipped off what I wanted for the aquarium.