  I discuss the formation of alpha-enhanced metal-rich stellar populations in
the nuclei of luminous ellipticals. Based on hierarchical clustering, different
galaxy formation scenarios, which imply different star formation histories, are
considered. In contrast to the fast clumpy collapse mode, the late merger of
two spiral galaxies fails to reproduce significantly $\alpha$-enhanced
abundance ratios, unless the IMF is flattened. Following the star formation
history predicted by semi-analytic models of hierarchical clustering for the
average elliptical, solar abundance ratios are obtained with Salpeter IMF.
According to the models, bright ellipticals in the field are expected to have
significantly lower Mg/Fe ratios than their counterparts in a cluster.
