Histogram showing normalized metallicity distributions of C_enh and C-normal stars. The top panel shows all stars combined, the middle panel shows high α stars only, and the bottom panel only low α stars. The differences between means is 0.26 dex in the top panel, 0.08 dex for high α stars and 0.30 dex for low α stars. No histogram for late high α stars is shown due to the small number of C_enh stars in this subpopulation.