prothallialadj.
/prəʊˈθalɪəl/, U.S. /proʊˈθæliəl/ Botany.
Of or relating to a prothallus.
ΘΚΠ
the world > plants > part of plant > reproductive part(s) > spore or sporule > cryptogam or plant having spores > [adjective] > of or having parts > of or having thallus
thalline1856
thalloid1857
thallodic1860
prothalline1868
thallodal1871
prothalloid1874
protonemal1875
prothallial1876
thalliform1891
protonematal1900
thalloidal1900
thallose1900
1876 J. H. Balfour in Encycl. Brit. IV. 160/1 In Ferns the alternation consists of two dissimilar generations,—a sexual or prothallial generation, and an asexual generation.
1905 Lancet 22 July 247/1 It is well known to fern fanciers and Dr. E. F. Bashford is apparently not acquainted with the fact that prothallial tissue is sometimes formed without any reduction taking place.
1995 Internat. Jrnl. Plant Sci. 156 367 Aspects of gametophyte growth, such as spore germination, filamentous growth, and prothallial growth.
Compounds
prothallial cell n. (in gymnosperms and certain pteridophytes) the smaller of two cells formed by the first asymmetric division of the microspore, sometimes undergoing further division and representing the vegetative tissue of the gametophyte.
ΚΠ
1897 Bot. Gaz. 23 428 To suggest that the small cell is a prothallial cell, homologous with the single prothallial cell of heterosporous pteridophytes.
1965 P. Bell & D. Coombe tr. Strasburger's Textbk. Bot. (new ed.) 593 In the originally unicellular microspore (pollen grain) [of Pinus] one or two (or sometimes more) small cells are formed at a particular spot just inside the wall; these prothallial cells often degenerate after a time.
2004 Developm. Biol. 269 320/2 The asymmetric divisions that occur during gametophyte development produce a prothallial cell, six sterile jacket cells, and two spermatogenous initials.
This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022).
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adj.1876