The grass radical sits on top, marking 苯 as something originally classed with plants. Coal-tar benzene was first isolated from plant-derived gum and aromatic resins, so the botanical radical fits the substance's nineteenth-century origin story.
Supplies the sound běn unchanged and was chosen by chemists to approximate the international name benzene. The root meaning is incidental, though aromatic chemistry literally takes 苯 as the root structure of countless derivatives — a quiet piece of luck.