The grain morphology of Si0.7Ge0.3 depends 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. (C) 1998 American Institute of Physics. [S0003-6951(98)02945-3].