AbstractSeidlitzia rosmarinus Boiss. has been identified as one of the potential species that could be used for rehabilitating degraded desert rangelands and salt‐affected soils due to its high salinity resistance and soil‐stabilizing ability. Morphological variation of 144 accessions of this species from 14 regions of the Isfahan province, Iran was investigated. The accessions studied were significantly different in terms of the traits recorded. Three forms of plant growth habit were observed, including spreading bush, erect bush, and shrub. The range of leaf dimensions was as follows: terminal leaf length: 1.57–7.22 mm, terminal leaf width: 0.91–3.34 mm, basal leaf length: 11.84–45.27 mm, and basal leaf width: 1.32–4.18 mm. Fruit diameter (with wings) ranged from 0.19 to 12.91 mm, and 100‐fruits dry weight varied between 0.11 and 0.76 g. A dendrogram created using Euclidean distances and the Ward's method revealed two main clusters. The obtained data revealed the morphological diversity within the studied populations. The reason for such a high diversity can be explained by a low probability of gene flow among the studied accessions. This is the first report on the application of morphological characteristics in the evaluation of the phenotypic variation of S. rosmarinus. This study presented a high phenotypic diversity of S. rosmarinus germplasm that could provide useful information for conservation and selection of cross‐parents in breeding.