Anatomical aspects of Asplenium adiantum-nigrum L. RODICA BERCU Department of Botany, Faculty of Natural Sciences and Agriculture, "Ovidius" University, 124 Mamaia Str., 8700 Constanza, Romania   Abstract The root of Asplenium adiantum-nigrum L. has a diarch structure, with modified layers of cortex around the stele and a monolayered pericycle. The rhizome (analyzed by serial transections) consists of an epidermis, a parenchymatous cortex and a centrally located dictyostele containing a variable number of meristeles. The leaf petiole and rachis exhibit a differential cortex (a sclerenchymatous hypodermis and an inner parenchyma). Close to the rachis tip, the sclerenchymatous hypodermis disappears. Remarkable are the variations in the organization of the vascular system. At the base of the leaf petiole, the vascular system is distelic, while up to the subterminal rachis, the monofascicular stele is X-shaped. The pinnulae have a homogenous mesophyll composed of branched and lobed cells. The veins have a collateral (midrib) and hadrocentric structure. The lower epidermis possesses many stomata of the polycytic and anomocytic types.   < back .