prothallus
Americannoun
noun
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The gametophyte of homosporous ferns and some other plants. Prothalli have chlorophyll for photosynthesis, but they are not differentiated into roots, stems, or leaves. They are usually small, flat, and delicate. Prothalli develop from germinated spores, and they bear both archegonia for producing eggs and antheridia for producing sperm.
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See more at alternation of generations
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of prothallus
From New Latin, dating back to 1850–55; see origin at pro- 2, thallus
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The large ones in germination produce a small prothallus; upon which the contents of the microspores act in the same way as in Ferns, and with a similar result.
From The Elements of Botany For Beginners and For Schools by Gray, Asa
A young prothallus of a Maiden-hair, moderately enlarged, and an older one with the first fern-leaf developed from near the notch.
From The Elements of Botany For Beginners and For Schools by Gray, Asa
The genus Ephedra, with its prothallus and archegonia, which are similar to those of other Gymnosperms, may be safely regarded as the most primitive of the Gnetales.
From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" by Various
I have already described how either side of the prothallus of a fern may be made to produce male or female organs, according as it is kept in the light or in the dark.
From The Biological Problem of To-day Preformation Or Epigenesis? The Basis of a Theory of Organic Development by Hertwig, Oscar
Similarly in the Araucarieae and in Widdringtonia the archegonia are numerous and scattered and often sunk in the prothallus tissue.
From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" by Various
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
