Dendritic patterns generated in non-equilibrium growth processes are prevalent in nature while their formation mechanisms are far from fully understood. Here, we report a coverage-dependent fractal degree evolution of monolayer 2H-MoS2 dendrites synthesized on a symmetry-disparate substrate of SrTiO3 (001). Surprisingly, various characterizations have revealed that the monolayer dendrites featured with orthogonal backbones are single crystalline, possessing both peculiar adlayer-substrate interaction and abnormal indirect bandgap on SrTiO3 (001). Further theoretical calculations indicate that a prominent diffusion anisotropy of monomer precursors, combined with the disparate adlayer-substrate symmetry, determine the diffusion-limited aggregation of MoS2 towards dendritic shapes. This work provides brand-new insights in the morphological engineering of two-dimensional atomic crystals, and contributes greatly to an in-depth understanding of the detailed dynamics in non-equilibrium crystal growth.