In the Friuli-Venezia Giulia Region (NE-Italy) three populations of Seseli elatum agg. occur, which have different altitude ranges and different ecology. It is generally difficult to distinguish these three taxa by classical taxonomical characters. This paper presents a first contribution to the solution of the problem. We have examined the classical morphological characters, plus microcharacters of the fruit surface (SEM), and the secretory structures (canals, ampullae, vittae). We propose some new discriminant characters. The morpho-anatomical variation seems to be correlated with a gradient of decreasing temperature and aridity, and increasing elevation. The anatomical variation corresponds with variation in the biochemical production. The numerical classification of ali characters indicates a rather isolated position of the population which occurs in xerophytic plant associations at low altitude.
