medullary ray

Collateral or bicollateral vascular bundle, developmental pith and medullary ray are obvious.

髓部发达，髓射线明显。

Ground meristem The central region of the apical meristem from which the ground tissues of pith, cortex, medullary rays, and mesophyll differentiate. In root meristem it is also called periblem.

位于顶端分生组的中部，髓、皮、髓射线以及叶肉这些基本组均是由基本分生组分化而成。根部分生组为皮原。