Had a Cabomba forest in my 42g angel tank. Mine developed roots quickly, The roots in the gravel were more while there were only less roots dandling mid-water and these were just straight.
You can brake these of and let the plant live just of the graveled roots,or just leave it be. Either way you have to prune them at least 2ice a week once their established otherwise they'll starve the lower portion of light. Mine put out runners just above the substrate and so multiplied and ancored themselves all-over the tank.