Pollen morphology of the Central European broomrapes (Orobanchaceae: Orobanche, Phelipanche and Orobanchella) and its taxonomical implications

Pollen grains of 450 samples of 25 species of the genus Orobanche and Phelipanche occurring in Central Europe were investigated using light and scanning electron microscopy. Palynological data on 18 species are reported here for the first time. The usefulness of micromorphological studies on pollen of Orobanche and Phelipanche is demonstrated. Previous research showed the separation of Phelipanche from Orobanche, a finding which is also supported by pollen aperture type and exine ornamentation. The pollen of Phelipanche is tricolpate, while that of Orobanche is inaperturate. Our research showed that one of the species included so far within Orobanche, namely O. coerulescens, has tricolpate pollen with microreticulate sculpture. As a consequence of the finding of tricolpate pollen and intermediate macromorphological characteristics of this species between Orobanche and Phelipanche, it is proposed to transfer it to a new genus, Orobanchella, described in the paper. A comparison of the main characteristics distinguishing Orobanche, Phelipanche, Boulardia and Orobanchella is also presented and discussed.