Can Ludwigia use biogenic decalcification? I didn't think they were one of the plants that could...
Anyway, they are able to chemically strip CO2 from HCO3-, basically leaving behind a hydroxyl ion, which creates a small area of increased pH surrounding plant leaves. The zone of increased pH lowers the solubility of the rest of the CaCO3 in solution, creating a white, flaky crust on leaves.
