The secondary phloem consisted of sieve cells and phloem parenchymas. 根的次生韧皮部则由筛胞和韧皮薄壁细胞组成。
In the secondary phloem of Tree Peony metaphloem was dominative in the root's secondary structure, which was just opposite to Herbaceous Peony. 根次生结构,牡丹根次生韧皮部占主要部分,而芍药根次生木质部占主要部分。