A Grammatical Dictionary of Botanical Latin

-thecium,-ii (s.n.III), abl. sg. thecio, in Gk. comp. (in fungi) “case, sac, capsule” (S&D), a little vessel or container; in generic names usually referring to a vessel in which spores, such as in mosses, or other diaspores are developed and dispersed; generally with the same meaning as -theca [> Gk. thekE (s.f.I), a container + dim. -ion > L. -ium];

- amphithecium,-ii (s.n.II), amphithecium; epithecium,-ii (s.n.II), epithecium; exothecium,-ii (s.n.II), exothecium; lomatothecium,-ii (s.n.II), lomatothecium.

Acanthothecium; Isothecium, referring to the capsule (theca) that is symmetrical or nearly so; Plagiothecium, > Gk. plagio, 'oblique,' and thEkion, a little vessel; in allusion to the capsule, which is usually oblique.

Note: new generic names derived from the names of closely related older genera ending in -theca (e.g. Cephalotheca) may be created in the standard way by forming the diminutive of the earlier name (e.g. Cephalothecium - both fungus genera). See also Acanthotheca > Acanthotheciella (diminutive ‘-ella’), Acanthotheciopsis (resemblance); Acanthothecis (an alternative ending) and Acanthothecium (diminutive ‘-ium’).

Thecium,-ii (s.n.II), abl.sg. thecio: thecium, 'a layer of tissue below the epithecium, which contains the sporangia in Lichens’ (Jackson, after Minks); ‘the hymenium (or fruit body) of Ascomycetes and lichens,” (Ainsworth & Bisby); the ascigerous layer of the Ascomycetes and ascolichens; the ascus hymenium (Snell & Dick); cf. epithecium, hymenium, hypothecium;

- hymenium (s.n.II) ascigerum (adj.A), abl. sg. hymenio ascigero: the thecium.

- [lichen] ‘Epithallus’ superficiem externam summam designat strati corticalis coloratam magisque saepe induratam, similiter ac ‘epithecium’ superficiem superam exprimit hymenii (sive thecii, ut quoque appellatur) (Nyl.), ‘epithallus’ designates the outer, highest surface, colored and more often indurate, of the cortical layer, similarly as ‘epithecium’ represents the upper surface of the hymenium (or of the thecium, as it is also called).

- [lichen] hymenium seu thecium contentum hypothecii indicat; thalamium thecasque complectitur et materia gummosa, lichenina, perfunditur, quam gelatinam hymeneam nominavi (Nyl.), the [sc. word] hymenium or thecium indicates the content of the hypothecium; it surrounds the thalamium and thecas and is soaked in a gummy material, licheninum, which I have called the hymenean gelatine.