Rootleaf was a food matter.
It was available in the Enterprise NX-01 galley. Doctor Phlox' Edosian slugs were partial to it in boiled form. When Phlox had two Tarkaleans in his sickbay, Captain Jonathan Archer offered to have some brought down to feed the slugs. Later, Hoshi Sato brought some (referring to it as "rootleaf lettuce") along with sustenance for him and his Pyrithian bat. (ENT: "Regeneration")