[α/Fe] vs. [Fe/H] for the open clusters, colour-coded by stellar age. The SPA clusters of this work are marked with a star symbol, while the cross and the triangle are the SPA clusters ASCC 123 and Praesepe, respectively; the transparent circles are the Gaia-ESO clusters with the abundances from Magrini et al. (2017) and the transparent diamonds are the APOGEE clusters with the abundances from Donor et al. (2020). The magenta dots (not colour-coded by age) in transparency are the field stars of the Gaia-ESO survey (public release, available at ESO archive). Finally, clusters in common between APOGEE and Gaia-ESO are linked by a black line.