Shù / mù / de / xíng / chéng / céng / fù / zé / chǎn / shēng / xīn / de / mù / zhì / bù / hé / rèn / pí / bù树木的形成层负责产生新的木质部和韧皮部。The vascular cambium of a tree produces new xylem and phloem.