Fruit and seed morphology of the genus Heracleum L. (Apiaceae) in Poland

The paper presents the results of a study on mericarps and seed morphology of four taxa occurring in Poland: Heracleum sphondylium subsp. sphondylium and subsp. sibiricum, H. mantegazzianum and H. sosnowskyi. Apart from selected biometric traits we analysed pericarps and seed-coat patterns using a stereoscopic microscope (SM) and a scanning microscope (SEM). Considerable diff erences in the dorsal surface of mericarps were observed, but major structural similarities were found on the ventral surface of mericarps. Pericarp surface diff ers signifi cantly between native and alien taxa in terms of secondary sculpture. The examined seeds were characterised by reticulate primary sculpture with diff erent size and shape of testa cells. The macro- and micromorphological characteristics of the mericarp and seeds may provide valuable additional diagnostic criteria for delimitation of Heracleum and can be used in the identifi cation of fruits and seeds