- a simple vegetative body undifferentiated into true leaves, stem, and root, ranging from an aggregation of filaments to a complex plantlike form.
Origin of thallus
1820–30; < New Latin < Greek thallós young shoot, twig
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for thallus
The colouring matter is ready formed and abundant in the thallus.Vegetable Dyes
Ethel M. Mairet
The thallus does not yet show this important morphological division.The Wonders of Life
The structure of the thallus may serve to represent that of most of the Lichens.An Elementary Text-book of the Microscope
John William Griffith
Antheridia immersed in the thallus, covered with dentate scales.
Piece of thallus of Parmelia conspersa, with section through an apothecium.The Elements of Botany
- the undifferentiated vegetative body of algae, fungi, and lichens
C19: from Latin, from Greek thallos green shoot, from thallein to bloom
Word Origin and History for thallus
Latin, from Greek thallos "green shoot, twig," related to thalia "abundance," thalos "scion, child," ultimately from PIE root *dhal- "to bloom" (cf. Old Irish duilesc, a type of algae).
Online Etymology Dictionary, © 2010 Douglas Harper
- A plant body or fungus undifferentiated into stem, root, or leaf.
- A type of body found among plants and fungi that is not differentiated into roots, stems, or leaves. Thalli are found among lichens, mosses, liverworts, and many algae, as well as the gametophyte generations of horsetails and ferns, which have rhizoids but not true roots.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.