From the wild

[yeti79]

Anyone able to identify this? Found in shallow water from local stream attached rock.

 

[yeti79]

Found the ID elsewhere. This is lake cress AKA Neobeckia aquatica, Armoracia aquatica, Amoracia lacustris, Rorippa americana, Rorippa aquatica. Says size is 7-10cm in submerged form. Does anyone have any experience with this plant?

 

[Willj626]

All I know about it is that it is an incredibly slow growing plant which keeps it from being too much of an invasive species concern.