Iran is one of the most diverse centers of wild tulip (Tulipa L.). In the present study, 208 accessions of this genus were collected from nine natural regions of Markazi province and two areas of Isfahan province. According to the morphological traits and diagnostic descriptions of the species, they were classified into six species including Tulipa systola Stapf, T. stapfii Turill, T. humilis Herbert, T. polychroma Stapf, T. biebersteiniana Schultes et Schultes f., T. montana var. montana Lindley, and T. montana var. chrysantha (Boiss.) Wendelbo. The species were evaluated using 44 morphological characters. Most of the traits showed a high degree of intraspecies variabilities, such as stem length, stem diameter, leaf dimensions, flower length, tepal length and width, and diameter and length of the bulb. In addition, considerable inter-species variability was found for blotch edge and shape of the inner tepal, leaf margin color, hair present in the middle part of the tunic, anther color, and stigma color. Based on the principal component analysis, seven significant components were obtained that explained 78.35% of the total variation among the species. UPGMA cluster analysis showed great variability among the accessions of each species and indicated that the studied plants can be a rich genetic source for breeding programs. Some of the accessions had a unique flower color, flower size, floral scent, stem length and bulb size which can be used in breeding programs.
