By combining transmission electron microscopy (TEM) and atomic force microscopy (AFM), the annealing behavior of polyethylene (PE) single crystals exhibited when annealed on highly oriented pyrolytic graphite (HOPG) was investigated. Morphologically, fibrils were formed and ordered in the form of a leaf venation in an annealed single crystal. From TEM observations, PE chains were found to lay down on the HOPG substrate surface, performing the epitaxial fitting with it; (110)(PE)//(0001)(HOPG) and < 001 >(PE)//< 11 (2) over bar0 >(HOPG). It was also confirmed that in veinlike fibrils forming the venation texture, molecular chains were oriented perpendicular to their length axis. The fibrillar crystals were chain-folded lamellae and were grown edge-on on the HOPG. Molecular orientation was crystallographically adjusted to the substrate through partial melting at a temperature below the melting point, performing lattice matching between polymer crystals and the substrate.