EN
Smyrnium perfoliatum L. (Apiaceae), an endangered summer forest herb grown in the understory of dominant oak-hornbeam stands in Devinska Kobyla, Little Carpathians region in SW Slovakia, is considered to form at least five leaf types of different physiological and anatomical quality. These observation are based upon the estimated differences of photosynthetic carbon dioxide uptake, chlorophyll content, leaf anatomy, and several quantitative parameters of growth analysis. There is a further attempt to establish, to what extent the daily changing environment, especially the excess of light of fast-moving sun-flecks by the photosynthetic apparatus within any leaf type, according to its dominant shade adaptation could be effectively used.