thallus

[ thal-uh s ]

/ ˈθæl əs /

noun, plural thal·li [thal-ahy] /ˈθæl aɪ/, thal·lus·es. Botany, Mycology.

a simple vegetative body undifferentiated into true leaves, stem, and root, ranging from an aggregation of filaments to a complex plantlike form.

Nearby words

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. 2019

Examples from the Web for thallus

The colors of the Thallus and apothecia of Lichens—their causes, and the circumstances which modify and alter them.
The Commercial Products of the Vegetable Kingdom|P. L. Simmonds
Another method is by the agency of little spores (zoospores) that are produced at the edges or extremities of the thallus.
The Sea Shore|William S. Furneaux
Flowering plants cannot have directly arisen out of thallus plants, nor out of mosses; but only out of ferns, or Filicines.
The History of Creation, Vol. II (of 2)|Ernst Haeckel
They are distinguished by possessing as gonidia algae foreign to the ordinary part of the thallus.
Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 5|Various

The thallus or body of the lichen is of very different form in different genera.
Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 5|Various

British Dictionary definitions for thallus

thallus

/ (ˈθæləs) /

noun plural thalli (ˈθælaɪ) or thalluses

the undifferentiated vegetative body of algae, fungi, and lichens

Derived Formsthalloid, adjective

Word Origin for thallus

C19: from Latin, from Greek thallos green shoot, from thallein to bloom

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

Word Origin and History for thallus

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).

Medicine definitions for thallus

thallus

[ thăl′əs ]

n. pl. thal•lus•es

A plant body or fungus undifferentiated into stem, root, or leaf.

Science definitions for thallus

thallus

[ thăl′əs ]

Plural thalli (thăl′ī)

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.