Palynological study of Polish taxa of Potentilla subsect. Collinae (Rosaceae)

Pollen grains of Potentilla subsect. Collinae Juz., i.e. P. collina Wibel, P. leucopolitana P.J. Müller, P. thyrsiflora Zimmeter, P. silesiaca Uechtr. and P. wimannania Günther et Schummel were studied with light and scanning electron microscope. Both viable and sterile pollen appeared in all taxa examined. The number of viable pollen ranged from 45.86% in P. leucopolitana to 59.95% in P. wimannania. The shape of pollen grains varies from prolate (dominating in all taxa studied except P. collina) to prolate-spheroidal. A size-diameter of the polar and equatorial axis of 18.3–22.9 11.9–17.5 mm was typical of P. collina and P. leucopolitana; and larger diameter of 23.1–30.6 15.8–22.4 mm of P. thyrsiflora, P. silesiaca and P. wimannania. The pollen is tricolporate with slightly striate ornamentation. Surface sculpture is not a good criterion to identify particular taxa from Potentilla subsect. Collinae. Except for P. leucopolitana, the pollen of which is characterized by much more marked striation, the pollen ornamentation was similar in all the specimens. Other characters such as the shape of style, the sepal to petal length ratio, the type of leaf division, the leaf pubescence of leaves as well as the sculpture of the fruitmay be valuable taxonomical criteria