Pollen diversity in the genus Carlina L. (subtribe Carlininae, Compositae) and its systematic significance

Pollen morphology of 19 species, 4 subspecies, and 1 variety of Carlina was studied in detail by light and scanning electron microscopy. Qualitative and quantitative pollen morphological characters which vary between taxa are found in the length of the ectocolpi, presence/nature of the echinae, pollen size and shape, lumina area, P/E ratio, polar axis, equatorial diameter, pollen shape, ectocolpi length, sculpture of ectoaperture membranes, area of lumina, and exine ornamentation. Three main pollen types are discerned: the C. atlantica type characterized by P/E <= 1.00, the C. curetum type characterized by P/E = 1.03-1.11, and the C. acanthifolia type with ratio P/E = 1.24-1.50. HCA and PCA analyses were carried out to detect the potential palynological characters which could be used to identify taxa. The data suggest that several pollen morphological characters can be used to delimit the taxa of Carlina. Dichotomous artificial keys based on palynological data are also given. (C) 2020 Published by Elsevier B.V.