Ever-increasing attention has been drawn to source specific multicast in the Internet society. In this paper, a novel multicast scheme, called Scalable Recursive Explicit Multicast (SREM) is proposed. To address the scalability problem, SREM uses a pair of branching node messages (BNMs) to construct a multicast tree, which is built up gradually and dynamically as of multicast group members join/leave . BNMs always traverse between a pair of branching node routers (BNRs) and the process of join/leave of member of a multicast session is carried out locally. Delivering multicast packets is carried out recursively between BNRs by unicast. In SREM, only BNs keep the multicast state about their next BNRs. By the cost analysis and simulation, it is shown SREM has many positive features such as fixed size control messages, being scalable and low join/leave latency.