Hair types in Polish selected taxa of Potentilla subsect. Collinae (Rosaceae)

Leaf hair types in Polish selected taxa from Potentilla subsect. Collinae Juz., i.e. P. collina Wibel s.str., P. silesiaca Uechtr. P. thyrsiflora Hillsen ex Zimmeter, P. wimanniana Gilnther and Schummel, P. leucopolitana P.J. Milller and P. leucopolitana P.J. Milller x P. incana P. Graebner were studied. A total of five unicellular hair types could be distinguished, based on the structure of the hair: straight, involuted, crispate, curved and stellate. The occurrence of involuted, curved and stellate hairs was observed for the first time for the majority of investigated taxa. There is a variation in density, position, as well as in the number of arms of stellate hairs. Although they are difficult to see without a stereo microscope, these differences seem to be systematically important. The study of hair types on surfaces of leaves supports the opinion that P. collina s.lato is a hybrid between P. argentea L. s.la-to, P. tabernaemontani Ascherson and P. incana P. Gaertner. Hairs form consistent characters which are highly suited for systematic purposes. The key to Polish taxa based on leaf hair types is given as well