Mass discrepancy plotted against luminosity for the 66 sources that have M_evol constrained by bonnsai. The upper dashed line is from the L(M) relation of helium stars; see main text for discussion. The lower line is M_spec = M_evol, and is a lower limit as stars cannot be under-luminous. The color denotes the surface helium abundance. Squares denote stars for which the LC is certain and triangles refer to the sources with weak Si iv relative to He i and for which the luminosity class may be debated (they may be dwarf stars). Helium enriched sources are all positioned above the one-to-one relation.