Protoderm The outermost layer of the apical meristem: the tissue that develops from the tunica initials of the apical meristem and gives rise to the epidermis and, in some plants, the root cap.

• 原表皮：指顶端分生组织的最外层：在植物中由起源于顶端分生组织的原套发育而来，并形成表皮。在根中，则形成根冠。