That's such an interesting look with the hydrocotyle growing out of the top like that . . . I like it! I didn't know it could stand up that much on its own; is it rooted in the cork back?
A bit of both, the Anubias and java root well to cork, then the pennywort piled on top of that.
I have a similar top growth/emergent mix without any CO2 on my ADA 60p as well.
But virtually no plants submersed. Moss provides the water conduit for upper reaches on that tank, unlike this tank. The pennywort flowered year round and I sold quite a bit of it back then(when folks would pay 20$ for a big bag of most any plant species).
I did not own a camera back then since my OM-1 Olympus was stolen a few years prior. This was a borrowed pentax k1000, then transferred (poorly) to a slide scanner. But you get the idea. I had a nicer front and center display a few times when I worked the riccia more.
I'm trying to remember where I first saw the riccia tied, I think it was German, who may have seen it from Amano before the English versions and the TFH started publishing it here. So there might be some indirect influence, but the cork is 100% dutch, I came up with the nails though and the view I wanted.