Growth pips on epitaxial {111} silicon films result when growth occurs preferentially around tripyramid hillocks which nucleate on the substrate surface and propogate ahead of the film; whiskers sometimes propagate from these. The tripyramids are often associated with and are the mirror image of stacking‐fault triangles. The stacking‐fault tetrahedra are not always complete or necessary for tripyramid formation. The studies indicate that both stacking faults and tripyramids propagate from twinned triangular deposits, the mechanism for stacking‐fault nucleation being a twinned deposited layer model. This model also accounts for the presence of microtwin lamellae recently reported around tripyramids. The possible whisker growth mechanisms are discussed in relation to the observations. The results indicate that a re‐entrant twin mechanism for whisker growth may operate in some cases.