These features may imply that, in branches of Zelkova serrata, the secondary phloem of the upper side (reaction phloem) may have a higher translocation efficiency.

• 此外，上侧次生韧皮部的筛管细胞较长也较宽，在两个筛管间具有的筛板亦较为水平排列，这些特徵可能意味著台湾榉的枝条上侧的次生韧皮部（反应韧皮部）具有较高的输送效率。