P. bifurcatum is a plant species with relatively high competency for regeneration. Several different tissue culture methods ( as noted in the introduction) have been successfully applied for its propagation. Tissue browning during culturing operations has rarely been described in these well-documented studies, except for P. stemaria (Hennen and Sheehan, 1978). However, in this study we observed that the explant browning in the GGB initiation stage causes serious and lethal effects, especially when large leaves or the distal sections of the incubated small leaves were used. This problem is greatly improved once GGB growth was initiated. It is no longer observed in the later culturing stages. The proper selection of explants turns out to be necessary and is sufficient to avoid this culturing barrier.