Pollen morphology of eight endemic Inula L. (Asteraceae) species in Turkey

The pollen morphology of eight endemic species of the genus Inula L. (Asteraceae)–I. helenium subsp. orgyalis (Boiss.) Grierson, I. helenium subsp. vanensis Grierson, I. macrocephala Boiss. & Kotschy ex Boiss., I. discoidea Boiss., I. sarana Boiss., I. fragilis Boiss. & Hausskn., I. anatolica Boiss. and I. sechmenii Hartvig & Strid–distributed in Turkey was studied with light microscopy and scanning electron microscopy. We found that the pollen of these Inula taxa are prolate-spheroidal in shape (except in Inula discoidea), with the polar axis ranging from 19.18 to 33.14 µm and the equatorial diameter ranging from 18.54 to 32.92 µm. The pollen grains are tricolporate and their ornamentation is echinate. The exine thickness ranges from 0.87 to 2.07 µm. As this study demonstrates, results of Principal Component Analysis are revealed that some of the pollen characters, such as spine length and width, are significant morphological characters for taxonomic discrimination of the eight endemic Inula taxa. According to cluster analysis, two main groups of examined taxa are constituted.