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Webster 1913 Edition
Prothallus
‖
Pro-thal′lus
,Noun.
pl.
Prothalli
(#)
. [NL., fr. Gr. [GREEK] before + [GREEK] a young shoot.]
(Bot.)
The minute primary growth from the spore of ferns and other Pteridophyta, which bears the true sexual organs; the oophoric generation of ferns, etc.