  An abundance analysis for 20 elements from Na to Eu is reported for 34 K
giants from the Hyades supercluster and for 22 K giants from the Sirius
supercluster. Observed giants were identified as highly probable members of
their respective superclusters by Famaey et al. (2005, A&A, 430, 165). Three
giants each from the Hyades and Praesepe open clusters were similarly observed
and analysed. Each supercluster shows a range in metallicity: $-0.20 \leq$
[Fe/H] $\leq +0.25$ for the Hyades supercluster and $-0.22 \leq $ [Fe/H] $\leq
+0.15$ for the Sirius supercluster with the metal-rich tail of the metallicity
distribution of the Hyades supercluster extending beyond that of the Sirius
supercluster and spanning the metallicity of the Hyades and Praesepe cluster
giants. Relative elemental abundances [El/Fe] across the supercluster giants
are representative of the Galactic thin disc as determined from giants in open
clusters analysed in a similar way to our approach. Judged by metallicity and
age, very few and likely none of the giants in these superclusters originated
in an open cluster: the pairings include the Hyades supercluster with the
Hyades - Praesepe open clusters and the Sirius supercluster with the U Ma open
cluster. Literature on main sequence stars attributed to the two superclusters
and the possible relation to the associated open cluster is reviewed. It is
suggested that the Hyades supercluster's main sequence population contains few
stars from the two associated open clusters. As suggested by some previous
investigations, the Sirius supercluster, when tightly defined kinematically,
appears to be well populated by stars shed by the U Ma open cluster.
