thecium (noun, pl. theciae;ascocarp term) – the hyphal layers of an apothecium derived directly from the primordium excluding the outermost layers; in the strict sense including epihymenium, hymenium and subhymenium, but not including the exciple, epithecium or hypothecium. The term thecium is not always used in this strict sense and sometimes used more or less equivalent to the term hymenium. In modern literature the term thecium is rarely used. Instead the hyphal layers that form this part of an apothecium are more often distinguished separately and described individually.