RESEARCHES ON ANATOMICAL ADAPTATIONS OF THE ALPINE PLANTS - PLANTAGO ATRATA

The anatomical analysis given in this work provides the first detailed description of Plantago atrata. The aim of present study is to understand the ecological adaptation to harsh environmental conditions. Plant samples have been collected from natural populations of the given location at July (2008). The effects of altitude (1802, 1525 and 1300 m) on some anatomical traits of leaves were studied. Anatomical studies have been carried out on the samples kept in alcohol 70%. Handle-blade sections have been taken for roots, aerial stems, rhizomes and leaves. The anatomical properties exhibited low variation from lower to higher elevation, except in the number of stomata. The leaves were amphistomatic. The ratio of stomata on the adaxial and abaxial leaf surfaces was similar in all growth conditions because the variations for stomatal densities were symmetrical. Low fluctuations were noticed in leaf thickness at the three altitudes. The mesophyll cells showed similar arrangement. Non-glandular and capitate hairs occurred in higher density on the leaf surface. Isolated lignified cells are found only in this species of the genus Plantago and contributes to rigidity leaves, expression of adaptation to wind stress. This study shows that stomatal density play an important role in plant adaptation to different altitudes. Rhizome are characterized by advanced lignifications by the presence of large groups of cells modified with lignified walls. Anatomical features indicate that the rhizomes are stored important nutritional reserves. On the other hand, flowering stems have less xylem, indicating a poor allocation of resources to reproductive organs. The results are presented with photographs and tables.