[Tiger15]

I bought this Mermaid weed from a LFS and it has gone through an amazing leaf transformation within weeks. The old emerged grown leaves are broad and lightly serrated, while the new submerged grown leaves are feathery like Ambulia but spiky, not soft, to touch. My submerged leaves look very different from the images depicted in plant profiles from nurseries. I understand the leaf shape of wild Mermaid is highly variable with locality strain, and most nursery grown Mermaid are Cuban strain with deeply serrated broad leaf. So I’m wondering if I have the Cuban strain or something else, or my peculiar growing conditions turned it spiky feathery. I have CO2, EI dosed, and medium light about 120 PAR at the water surface and 50 at substrate level.

 

[Tinanti]

I think the Cuban one still has leaves that are not as finely pinnatisected as what you have. The plants we see here in Maryland look more like what you have, though I didn't know any finer leaved stuff was sold commercially. Must be.