pro·​thal·​lus (ˌ)prō-ˈtha-ləs How to pronounce prothallus (audio)
: the gametophyte of a pteridophyte (such as a fern) that is typically a small flat green thallus attached to the soil by rhizoids
: a greatly reduced structure of a seed plant corresponding to the pteridophyte prothallus

Illustration of prothallus

Illustration of prothallus
  • 1 antheridium
  • 2 archegonium
  • 3 rhizoid

Word History


New Latin

First Known Use

1854, in the meaning defined at sense 1

Time Traveler
The first known use of prothallus was in 1854

Dictionary Entries Near prothallus

Cite this Entry

“Prothallus.” Dictionary, Merriam-Webster, Accessed 22 Jul. 2024.

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