ZnMgO pleated nanosheets and quasinanotubes were synthesized in the same region on Si substrate using [Mg(H2O)(6)](NO3)(2) and zinc diethyl as the reactant source. The nanosheets are periodically pleated with the angles of 120 degrees and 60 degrees between two adjacent pleats. Some of the nanosheets fold into quasinanotubes. Homoepitaxial interconnections are observed at the boundaries of the pleats, and the whole pleated nanosheet is a single wurtzite crystal. The growth mechanism is discussed, which is proposed to be a combination of vapor-solid process of two-dimensional growth of the ((1) over bar2 (1) over bar0) planes and their random along the < 10 (1) over bar0 > directions. (c) 2007 American Institute of Physics.