Stratose thallus, where the tissues are in horizontal layers, [70].

Stratum, a layer of tissue in the thallus, [70].

Symbiont, one of two dissimilar organisms living together, [32].

Symbiosis, a living together of dissimilar organisms, also termed commensalism, [31, 32 et seq.]

Tegulicolous, living on tiles, [369].

Terebrator, boring apparatus, term used by Lindau for the lichen “trichogyne,” [179].

Thalline margin, an apothecial margin formed of and usually coloured like the thallus; [cf. amphithecium].

Thallus, vegetative body or soma of the lichen plant, [11], [421]. Endogenous thallus in which the alga predominates, [68]. Exogenous thallus in which the fungus predominates, [69].

Theca, enlarged cell containing spores; [cf. ascus].

Thecium, layer of tissue in the apothecium consisting of asci and paraphyses; [cf. hymenium], [157].