[proh-tuh-zahy-luh m, -lem]

noun Botany.

the part of the primary xylem that develops first, consisting of narrow, thin-walled cells.

Origin of protoxylem

First recorded in 1895–1900; proto- + xylem Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for protoxylem



the first-formed xylem tissue, consisting of extensible thin-walled cells thickened with rings or spirals of ligninCompare metaxylem
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

protoxylem in Science



The first formed xylem that differentiates from the procambium.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.