We report in this article a mechanism to form regularly zigzag branch of CsCl crystallites on a flat glass substrate, in which the crystallographic orientation rotates continuously, and a pattern with long-range order on tens of micrometer scale is generated. Atomic force microscopy (AFM) indicates that this unusual crystallization behavior is associated with successive nucleation at the concave edge of crystallite facet and glass substrate, where interfacial tension underneath the nucleus is asymmetric. We suggest that these observations reveal a new lateral growth mode, and may help to understand a class of long-range ordering effect in crystallization. (C) 2007 Elsevier B.V. All rights reserved.