  Staggered $t$-structures are a class of $t$-structures on derived categories
of equivariant coherent sheaves. In this note, we show that the derived
category of coherent sheaves on a partial flag variety, equivariant for a Borel
subgroup, admits an artinian staggered $t$-structure. As a consequence, we
obtain a basis for its equivariant $K$-theory consisting of simple staggered
sheaves.
