secondary cambium

Secondary vascular tissue, found only in plants with secondary thickening , develops from the vascular cambium.

次生维管组织由维管形成层发育而来, 仅存在于有次生加厚的植物中.

As the vascular cambium was initiated, the interfascicular cambium was formed on the adaxial side of secondary phloem produced by the cambium. phloem developed well;

但是当维管形成层形成时，束间形成层在初生乳管的近轴一侧产生，因而随着次生形成层的活动，初生乳管被定位于次生韧皮部远轴一侧。

The primary xylem of root is diarch, of which developmental process contains primary growth and secondary growth. Secondary growth mainly depends on the activity of the vascular cambium and cork cambium.

其根为二原型，发育过程可分为初生生长和次生生长，成熟根的结构以次生结构为主，次生生长主要依靠维管形成层和木栓形成层的活动来完成。

The secondary growth mainly relied on activities of vascular cambium and cork cambium.

次生生长主要是依靠维管形成层和木栓形成层的活动来完成。

With the progressive development of stem, the activity of vascular cambium began. The fascicular cambium differentiated into secondary xylem and secondary phloem, while the interfascicular cambium only differentiated into wide ray of parenchyma tissue.

随着茎的继续发育，维管形成层开始活动，由束中形成层产生次生韧皮部和次生木质部分子；而束间形成层仅产生薄壁细胞组成宽的射线。

While for older roots, there are periderm, secondary phloem, cambium, secondary xylem and primary xylem. In root, the duct caliber of xylem in Akebia quinata ( Thunb.) Decne.

老根由外向内依次为：周皮、次生韧皮部、形成层、次生木质部、初生木质部。在根中五叶木通木质部导管口径比三叶木通的大很多。