| چکیده انگلیسی مقاله |
The genus Nerium L. consists of perennial shrubs belonging to the Apocynaceae family, which are widely found in the warm and dry regions of western, southern, and southeastern Iran as wild plants. In this study, the quantitative and qualitative morphological traits of various Nerium populations across different regions of Iran were examined. Samples were collected from 100 individuals belonging to 38 different populations, and their morphological data were analyzed. Cluster analysis and Principal Component Analysis (PCA) were performed using the R software. The results indicated that leaf size, flower corolla color, and corolla appendages are highly valuable taxonomic traits and can aid in distinguishing different populations. However, taxonomic ambiguities persist regarding the overlap of certain morphological traits and the exact definition of subspecies. Therefore, molecular studies are recommended to resolve these ambiguities and confirm the results of morphological analyses.
Keywords: distribution, Apocynaceae, Nerium, subspecies, taxonomy.
Introduction
The Apocynaceae family, consisting of over 415 genera and more than 5,000 species, is among the largest families of flowering plants. The genus Nerium L., belonging to this family, consists of perennial shrubs found in various geographical regions, particularly in the Mediterranean, southern Asia, and parts of America and Australia. In Iran, Nerium oleander L. grows predominantly in riverbeds within warm and arid regions. The plant holds significance not only as an ornamental species but also for its medicinal properties, being used in traditional medicine for its cardiotonic, anti-inflammatory, and antimicrobial properties, among others. Flora Iranica and Flora of Iran list two subspecies within the genus: Nerium oleander subsp. kurdicum and Nerium indicum subsp. kotschyi. These subspecies are primarily distinguished by key morphological traits, such as the shape and size of the corolla appendages. N. oleander subsp. kurdicum is characterized by short, toothed corolla appendages, while N. indicum subsp. kotschyi has long, thread-like corolla appendages. Despite these distinctions, the current taxonomic treatment on major botanical databases (e.g., POWO and IPNI) consider these subspecies synonyms of Nerium oleander. This study, therefore, aims to provide a comprehensive morphological and morphometric analysis to clarify the taxonomic status of these subspecies in Iran.
Materials & Methods
This study began with a review of the literature and examination of herbarium specimens (Rechinger, 1974; Dinarvand, 2002). Field samples were then collected from 100 individuals across 38 different populations in various regions of Iran, including Ilam, Bushehr, Khuzestan, Fars, Kerman, Kermanshah, and Hormozgan provinces. Sampling was designed to cover the natural distribution of Nerium in Iran. The collected specimens were pressed, dried, and stored in the herbarium of the Agricultural and Natural Resources Research Center of Isfahan Province (SFAHAN). Morphological data were recorded and analyzed using cluster analysis and Principal Component Analysis (PCA) through the R software.
Research findings
Morphological analysis revealed significant variation in leaf size, petal length, and the size of corolla appendages across different populations. Ward's method of cluster analysis indicated two primary clusters corresponding to the western (Ilam and Kermanshah) and southern populations. The key differentiating traits between these clusters were leaf size, flower corolla color, and corolla appendages. The results of PCA also supported this differentiation, with the first and second principal components explaining most of the variance in the morphological data, highlighting the importance of these traits in subspecies identification.
Discussion of Results & Conclusion
This study confirms that the morphological traits examined, particularly leaf size, corolla color, and corolla appendages, have significant taxonomic value for distinguishing Nerium populations in Iran. However, the study also identifies persistent taxonomic ambiguities related to the overlap of certain morphological traits among subspecies. These ambiguities suggest that further molecular studies are necessary to confirm the morphological findings and resolve the taxonomic status of the subspecies. The study contributes to a better understanding of Nerium diversity and provides a foundation for future molecular and conservation studies in Iran.
|