prothallium

American  

[proh-thal-ee-uhm] / proʊˈθæl i əm /

noun

PLURAL

prothallia

1. Botany.  the gametophyte of ferns and related plants.

2. the analogous rudimentary gametophyte of seed-bearing plants.

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Other Word Forms

• prothallial adjective
• prothallic adjective
• prothalline adjective
• prothalloid adjective

Etymology

Origin of prothallium

1855–60; < New Latin < Greek pro- pro- ² + thallíon, diminutive of thallós young shoot; -ium

Example Sentences

These are called the “endosperm cells,” but differ from the endosperm cells of the gymnosperms, in the fact that they are not developed until after fertilization, and can hardly, therefore, be regarded as representing the prothallium of the gymnosperms and pteridophytes.

From Project Gutenberg

I, vertical section of the female prothallium of Selaginella, × 50. ar. archegonium.

From Project Gutenberg

Even before the spores are ripe the development of the prothallium begins, and this is significant, as it shows an undoubted relationship between these plants and the lowest of the seed plants, as we shall see when we study that group.

From Project Gutenberg

In studying the development of the antheridia, it is only necessary to mount the plants in water and examine them directly; but the study of the archegonia requires careful longitudinal sections of the prothallium.

From Project Gutenberg

After a time growth ceases, and is not resumed until the development of the female prothallium and archegonia is nearly complete, which does not occur until more than a year from the time the pollen spore first reaches the ovule.

From Project Gutenberg