This study concerns ecological, morphological and anatomical characteristics of Heracleum platytaenium which is a monocarpic and also an endemic species in the Central Black Sea region of Turkey. N, P dynamics in stem, leaves and roots, morphological and anatomical characters, and soil properties along an elevation gradient were investigated. N and P concentrations varied along the elevation gradient and during the growing season in both basal and stem leaves. N concentrations of root, stem and flower did not change significantly during the growing season, although significant changes were observed along the elevation gradient. N concentrations of roots and stems increased, although N concentrations of flowers declined along topographic gradient. P concentrations also varied along the elevation gradient and during the growing season in root, stem and flower. There are secretory cavities in stem and petiole. Vascular bundles are arranged in two lines in the petiole. There are 11 bundles in outer line and 4 bundles in inner line. The basal leaf is dorsiventral. The cauline leaf has homogeneous mesophyll. Stomata type is anomocytic in both basal and cauline leaves.
Keywords: nitrogen, phosphorus, dynamics, Heracleum platytaenium, morphology, anatomy, monocarpic plant.