Thanks. I have about 30 or so plantlets of parva out there. I dont' want a full carpet of it. Right now, they sort of group with the rocks. The marsilea will fill in the foreground.
I have C. crispatula var Balansae (emersed so not tall) in there now. Ordered a pot hoping it would have a few (3-4) plantlets to divide, but only had one large one with some potential runners. I'll likely have to get some more.