次生加厚分生组织切向分裂，向外侧产生的细胞分化成薄壁组织；
The secondary thickening meristem divided in tangent .
次生加厚分生组织起源于正常的散生维管束中柱外侧的薄壁组织细胞。
The secondary thickening meristem originated from the parenchyma cells , which were located the outside of the atactostele .
次生分生组织次生分生组织次生分生组织