Lithium abundances in Galactic globular and open clusters, and field stars, plotted versus metallicity. We show the mean (filled green rectangles), minimum, and maximum values (small black dots connected by vertical solid lines), and 25% and 75% quantiles (black horizontal bars) of lithium abundances as derived in unevolved stars of Galactic globular clusters M 92, NGC 6397, ω Cen, NGC 6752, and 47 Tuc, and the old, metal-poor open cluster NGC 2243 (filled blue triangle, ~4.4 Gyr, Kaluzny et al. 2006, see also Table 7 for details). The data for open clusters (open blue triangles) were taken from Sestito & Randich (2005), with each datapoint typically representing averages for several open clusters in a given age bin (ages are indicated by numbers next to the symbols, in Gyr, error bars in this case mark 1σ spread in lithium abundances). Data for the Galactic field stars (filled and open circles) were taken from Lambert & Reddy (2004) and are shown for two age sub-groups: stars that are older than 10 Gyr (filled circles) and stars that are younger than 2 Gyr (open circles). The solid green line shows theoretically predicted evolution of the Galactic lithium abundance from Prantzos (2012).