from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A small, flat, delicate structure produced by a germinating spore and bearing sex organs. It is the gametophyte of ferns and some other plants.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A prothallium.
from the GNU version of the Collaborative International Dictionary of English
- n. The minute primary growth from the spore of ferns and other Pteridophyta, which bears the true sexual organs; the oöphoric generation of ferns, etc.
from The Century Dictionary and Cyclopedia
- n. Same as prothallium.
New Latin : pro-2 + Greek thallos, shoot (from thallein, to sprout).(American Heritage® Dictionary of the English Language, Fourth Edition)