Scorzonera L. is represented by 57 species in Iran including three subgenera: S. subg. Scorzonera, S. subg. Podospermum and S. subg. Pseudopodospermum. Species of S. subg. Podospermum and S. subg. Pseudopodospermum in Iran are morphologically similar, which limits species delimitation. In order to clarify intersubgeneric and interspecific delimitation in Iran, we carried out extensive sampling of the two subgenera in Iran. We conducted phylogenetic analyses based on the nuclear Internal Transcribed Spacer (nrITS), detailed morphological studies, and we evaluated the systematic value of achene features. Our results showed that Scorzonera s.l. is polyphyletic, and both S. subg. Podospermum and S. subg. Pseudopodospermum are monophyletic. The monophyly of S. subg. Podospermum morphologically corresponds to a combination of characters containing pinnatifid leaves, phyllaries with black corniculate projections, and the presence of a swollen carpopodium on the achenes. A comparison of the topology observed in the nrITS phylogeny with achene features indicates that a sculptured achene wall surface in members of S. subg. Pseudopodospermum provides a synapomorphy for this lineage. This study supports a broader circumscription of S. subg. Pseudopodospermum with the addition of S. calyculata (S. sect. Incisae), S. ovata, S. papposa and S. paradoxa (S. sect. Papposae). Finally, we provide a taxonomic treatment, including an identification key and species diagnoses and distributions, with nomenclature of Iranian species.
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