n.前形成层
The first formed xylem that differentiates from the procambium. 原生木质部最先形成的木质部，与原形成层不同
Primary xylem Xylem derived from the procambium in the young plant. 初生木质部：指幼嫩植物中来源于原形成层的木质部。
Primary phloem PHLOEM derived from the procambium in the young plant. 初生韧皮部：指幼嫩植物中来源于原形成层的韧皮部。
Cells of the procambium and ground meristem are more vacuolated than those of the protoderm. 原形成层和基本分生组织的细胞比原表皮层细胞更加液泡化。
Protophloem The first-formed PRIMARY PHLOEM, differentiated from the procambium in the region just behind the meristem. 原生韧皮部：最早形成的初生韧皮部，由位于分生组织中的原形成层分化而来。
