You can?You can pretty much grow all the stem pants without a substrate.
What I find is that most stem plants tend to float if not anchored in some way. I’ve kept a 29 gallon tank without a substrate for many years. Mostly it is Java Fern on wood but I always tuck a few stems in there to liven it up. Right at the moment there is persicaria, hydrocotyle, myriophyllum , ammannia trifolia, and some rotalla growing in that tank. I am also growing out a sword stalk with two or three plantlets in that tank. Star grass does really well as a floating plant. Alternathera does well. Hygropilas do well.You can?