protostele
/ˈproʊtoʊˌstil/
noun
- The simplest and most primitive type of central cylinder in the stems and roots of certain plants, consisting of a solid core of vascular tissue without a central pith.
- Unlike more advanced plants, a protostele lacks a central pith region.
- Ferns and some early land plants have a protostele in their stems.
- The protostele is an important feature in the study of plant evolution.