[ proh-tuh-steel, -stee-lee ]
/ ˈproʊ təˌstil, -ˌsti li /

noun Botany.

the solid stele of most roots, having a central core of xylem enclosed by phloem.

Origin of protostele

First recorded in 1900–05; proto- + stele

Related forms

pro·to·ste·lic [proh-tuh-stee-lik] /ˌproʊ təˈsti lɪk/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for protostele

  • In the Coal Measure period, however, the protostele was characteristic of one of the two main groups of ferns.

    Ancient Plants|Marie C. Stopes
  • In its simplest form (as in fig. 36) it is called a protostele, and is to be found in both living and fossil plants.

    Ancient Plants|Marie C. Stopes

British Dictionary definitions for protostele


/ (ˈprəʊtəˌstiːl, -ˌstiːlɪ) /


a simple type of stele with a central core of xylem surrounded by a cylinder of phloem: occurs in most roots and the stems of ferns, etc

Derived Forms

protostelic, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for protostele


[ prōtə-stēl′, prō′tə-stēlē ]

The most primitive form of stele, consisting of a solid core of xylem encased by phloem or of xylem interspersed with phloem. The roots of all vascular plants, as well as the stems of lycophytes, have protosteles.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.