A Grammatical Dictionary of Botanical Latin

Prothallium,-ii (s.n.II), abl. sg. prothallio, also prothallus,-i (s.m.II), q.v., abl. sg. prothallo: “a thalloid oophyte or its homologue resulting from the germination of a spore, usually a flattened leafy expansion and bearing sexual organs” (Jackson); the prothallus (bryophytes) “a small, undifferentiated thallus, loosely used for a thalloid protonema; e.g. Sphagnum” (Magill 1990): prothallium,-ii (s.n.II), abl. sg. prothallio, nom. & acc. pl. prothallia; syn. prothallus; syn. sporeling, q.v.; cf. protothallus,-i (s.m.II); see thallus,-i (s.m.II);

- (moss) [Micromitrium] plantae minutissimae in prothallio bysoideo diu persistente sed inconspicuo nidulantes (Austin), plants very tiny, nestling in a long-persisting cottony but inconspicuous prothallium.

Archegoniophorum,-i (s.n.II), abl. sing. archegoniophoro: archegoniophore, “the stalk or other outgrowth of a prothallium upon which archegonia are borne (as in liverworts of the genus Marchantia)” (WIII).

Herpoblast: “Cramer’s term for a confervoid prothallium lying flat on its substratum” (Jackson): herpoblastus,-i (s.m.II), abl.sg herpoblasto.

NOTE: endosperm, q.v., “in Gymnosperms the prothallium within the embryo sac” (Jackson).

NOTE: endosperm, q.v., “in Selaginella, tissue formed in the cavity of the macrospore below the prothallium” (Jackson.)

NOTE: “1. the gametophyte of a fern or other pteridophyte that is typically a small flat green thallus attached to the soil by rhizoids but is sometimes filamentous and branching, that occasionally forms a subterranean tuberous mass, or that rarely (as in the club mosses) develops within the megaspore by which it is produced, 2. any of various structures (as several cells of the pollen grain or in gymnosperms of the megaspore) that in seed plants correspond to the pteridophyte prothallium” (WIII).

NOTE: prothallium,-ii (s.n.II) is a synonym of ‘sporeling,’ q.v. (WIII).