  We apply collinear expansion to inclusive hadron production in $e^+e^-$
annihilation and derive a formalism suitable for systematic study of leading as
well as higher twist contributions to fragmentation functions at the tree
level. We make the calculations for hadrons with spin-0, spin-1/2 as well as
spin-1 and obtain the results in terms of different components of fragmentation
functions for the hadronic tensors, the differential cross section as well as
hadron polarizations in different cases. The results show a number of
interesting features such as the existence of transverse polarization for
spin-1/2 hadrons at the twist-3 level, the quark polarization independence of
the spin alignment of vector mesons.
