n.
Pronunciation: ( ˌ )pr ō - ' tha-l ə s
Function: noun
Etymology: New Latin
Date: 1854
1 : the gametophyte of a pteridophyte (as a fern) that is typically a small flat green thallus attached to the soil by rhizoids
2 : a greatly reduced structure of a seed plant corresponding to the pteridophyte prothallus
prothallus 1: 1 antheridium, 2 archegonium, 3 rhizoid