the most relectual (primitive) form of a stele with a central, solid rod of vascular tissues. Various types (halplostele, plectostele, actinostele) describe the distribution of xylem and phloem.
Stele having a solid column of vascular tissue with xylem centrally located.
When a plant's vascular tissue develops in a solid central bundle, it is said to have a protostele. See also siphonostele and eustele.
a solid core of conducting tissues where phloem surrounds xylem. Protostele plants lack a central pith