Found in a pond in the Wairarapa. I know the wee floating critter is Lemna disperma. Not sure about the fully submerged plant - paired opposite leaves that are at 90 degrees to the next pair of leaves. Or the greyish looking plant - leaves alternate, very thin leaves, midvein protrudes on the undersurface, lateral veins angle off the main vein but are indistinct.
Thanks from Astrid