cortex

noun

(L. cortex: bark, rind, shell, husk) (pl. cortices) In rhizomes and other axes, the tissue between the stele and the epidermis; in lichens, the outermost layer of the thallus; in seaweeds and fungi the tissue external to the central tissue of longitudinal cells; in plants, the typically parenchymatous layer of tissue external to the vascular tissue and internal to the corky or epidermal tissues of a green plant; broadly: all tissues external to the xylem; in bryophytes, the stem tissue located between the central strand and epidermis, either of which may not be differentiated; often used in liverworts to denote the differentiated outer rind or epidermal cell layer of the stem; in lichens, the outermost layer of the thallus which, if present, consists of compacted hyphae which may appear either fibrous or cellular. Cf. epidermis, medulla.