The Balkan endemic Picris hispidissima (Compositae): morphology, nuclear DNA content and relationship to the polymorphic P. hieracioides.
Abstract
The only Balkan endemic of the genus Picris, Picris hispidissima, was studied in detail using morphological and karyological methods. The species was shown to be morphologically distinct from the closest taxon, Picris hieracioides, by the pectinate-ciliate indumentum of involucral bracts, dilatation of the peduncle, length of the outer and inner bracts, and indumentum colour.
No morphological variation that would require taxonomic classification was found within this species. Despite the diploid chromosome number (2n = 2x = 10) being confirmed for P. hispidissima, variation of up to 9.5% in genome size was found.
The likely explanation for this variation is hybridization and introgression with closely related P. hieracioides. The most convincing evidence for this hypothesis is the detection of plants with two clearly different DNA contents arising from a single capitulum found in the location where P. hispidissima and P. hieracioides co-occur.