B. Papp szerk.: Studia Botanica Hungarica 38. 2007 (Budapest, 2007)

Bercu, Rodica: On the anatomy of the endangered plant species Asplenium lepidum (Aspleniaceae)

MATERIALS AND METHODS Cross sections of the root, rhizome and leaf (petiole and bade) of specimens, preserved in the Herbarium and Botanical Garden "Alexandru Borza" in Cluj-Napoca (Kolozsvár/Clausenburg), were prepared using a rotary microtome. The samples were stained with alum-carmine and iodine green and were embedded in Canada balsam. Observations were made with a BIOROM-T bright field microscope, equipped with a TOPICA-6001A video camera. The microphotographs were obtained from the video camera through a computer. The adventitious root, in cross sections, revealed that the cortex consists of few layers of compactly arranged parenchyma cells. The inner layers of cortex cells are modified and have thick walls. KROEMER ( 1903) has suggested that this wall thickening is the result of cutinised blade superpositions. Noticed by early authors, the presence of such "curious cells" around the stele have led to the recognition of this tissue belonging to the stele and naming it "sclerenchymatous mass" (RUSSOW 1872, BIERHORST 1971) or a "stereomic sheath" (DE BARY 1877, OGURA 1938, BERCU 2004, 2005, 2006) (Fig. 1A, B). This configuration has led SCHNEIDER (1996) to include this type of root to that of Asplenium (Fig. 1A, B). Fig. 1. Cross section of the adventitious root. A: general view of the root (xl50); B: detail of the stele (x240). (Co = cortex, Mx = metaxylem, Pc = pericycle, Ph = phloem, Px = protoxylem, St = stele, SS = stereomic sheath (orig.)). RESULTS AND DISCUSSION