NORDIC JOURNAL OF BOTANY, vol.29, no.1, pp.26-37, 2011 (SCI-Expanded)
Two new species of Cirsium Mill. from east Anatolia (Turkey): C. sivasicum Yildiz, Arabaci & Dirmenci and C. peshmenianum Yildiz, Dirmenci & Arabaci, are described and illustrated. Both new species belong to C. sect. Epitrachys DC. (Asteraceae: Cardueae) and are closely related to C. rigidum DC., C. leuconeurum Boiss. & Hausskn. and C. karduchorum Petr. The differences between the new species and their allies are discussed and a diagnostic key is provided. A detailed description of a previously poorly known species, C. leuconeurum, is also provided. The pollen grain morphology of the new species and their allies were investigated with light and scanning electron microscopes. Based on the shape of the spines and the surface ornamentation, the pollen grains of the species were divided into 3 types: C. rigidum and C. sivasicum (type I), C. leuconeurum and C. pesmenianum (type II), C. karduchorum (type III).