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 seed-like structure afforded protection to the prothallus, and may have enabled the embryo to be launched on the world in greater security.
From Darwin and Modern Science by Seward, A. C. (Albert Charles)
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 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
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
Investigation of this prothallus under the microscope resulted in the discovery of a wholly unsuspected kind of fertilization, taking place at this germinating stage of the plant.
From The Elements of Botany For Beginners and For Schools by Gray, Asa
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.
