The grain morphology ofSi0.7Ge0.3depends on the number of the primary noncoplanar twin variants formed at the early stage of solid-phase crystallization. The grain with major twin bands of a single twin variant parallel to a {111} plane develops an elongated shape, owing to the preferential growth in a ⟨112⟩ direction along twins. When the grain has major twin bands of two or more noncoplanar twin variants, the growth front between noncoplanar twin bands develops as fast as the ⟨112⟩ direction along twins propagates, because such a growth front is formed from a {111} ledge. As results, the grain becomes more or less equiaxed due to the increasing number of primary, noncoplanar twin variants. ©1998 American Institute of Physics.