Thallus
/ˈθæl.əs/noun
The undifferentiated body of a plant, alga, fungus, or lichen, not divided into true roots, stems, and leaves.
Did you know?In classical Greek, the same root behind *thallus* was tied to budding and flourishing growth, which is why modern biology uses it for organisms that seem to appear as a single living sheet or branchless body.
Etymological Timeline
Proto-Indo-European
PIE
*dʰel-
“to bloom, sprout, or flourish”
Ancient Greek
Greek
θάλλος (thállos)
“a green shoot, twig, or young bloom”
Latin
Latin
thallus
“borrowed scientific term for a plant body or shoot”
18th–19th Century
New Latin
thallus
“used in botany for an undifferentiated vegetative body”
Modern English
English
thallus
“the body of an alga, fungus, or lichen lacking true roots, stems, and leaves”
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