Mushroom structure exhibits unique electromagnetic properties that have led to a wide range of applications in the microwave and antenna community. This article concentrates on the electromagnetic band-gap characteristic of the mushroom structure with the suspending microstrip line, and a new concept of the mushroom interlaced periodic arrayal is proposed. Furthermore, we utilize the new concept to design a triband bandstop filter and a triplexer. The triplexer can integrate three kinds of communication systems with each other, which operate at frequencies including GSM 1800 MHz, WiFi 2.45 GHz, and WiMAX 3.5 GHz, respectively. Therefore, the novel triplexer would be good potential candidate not only for nowadays but also for future applications in communication systems.