Eichornia Diversifolia

My Eichornia Diversifolia does not seem to have ribboning on its leaves. They really should have a ribbon or slightly hammered appearance. Is this something that happens to the plant under less than ideal conditions or is it possible I have the wrong plant (perhaps H. Zosterfolia)? I do have the general blackening of the lower part of the plant which is typical of E. Diversifolia.

Thanks for any advice. - Chris