mesosporiumn.
/ˌmɛsə(ʊ)ˈspɔːrɪəm/, U.S. /ˌmɛzoʊˈspɔriəm/; see also meso- comb. form. Botany and Mycology.
The middle layer of the wall of any of several types of three-layered spores, esp. of the ascospore of a fungus. Cf. mesospore n.
ΘΚΠ
the world > plants > part of plant > reproductive part(s) > spore or sporule > [noun] > parts of or related to > other parts of
endospore1875
mesospore1882
mesosporium1882
sporoplasm1893
1882–4 M. C. Cooke Brit. Fresh-water Algæ I. 109 The cell-contents surround themselves with a new layer of cellulose (mesosporium) within the original one (exosporium).
1955 G. M. Smith Cryptogamic Bot. (ed. 2) II. iii. 36 The median layer (mesosporium) [sc. in Riccia curtisii, a liverwort] is thick and composed of three concentric zones.
1993 Philos. Trans. (Royal Soc.) B. 339 483 Ascospore walls comprise a bipartite mesosporium, a thinner electron-opaque episporium and an outer mucilaginous sheath.
1999 Mycologia 91 326 Ascospores are verrucose, with projections arising from the outer mesosporium and surrounded by the episporium.
This is a new entry (OED Third Edition, September 2001; most recently modified version published online March 2022).
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n.1882