that protocorm had the highest embryo induction frequency (100% embryogenesis) among leaf segment, apical bud, single node, and crown. SEs were also formed from protocorm and stem explants when cultured on hormone-free medium. This result suggests that the endogenous hormone inside the explants might still have a role in embryo formation. Consistent with our result, Kaewubon and Meesawat (2016) also reported that bisected protocorm of Pigeon orchid (Dendrobium crumenatum) cultured on PGRS-free medium could formed SES.