تاکسونومی و بیوسیستماتیک (Aug 2022)
An Anatomical, Micro-Morphological, and Ecological Study of Acantholimon cymosum (Plumbaginaceae) Endemic to Iran
Abstract
The species Acantholimon cymosum with the Persian name Gypsophil Kolah Mirhasan or Cyme Kolah Mirhasan is endemic to Iran and has a limited distribution in the gypsum soils of the west and northwest of Semnan. A sampling of soil and plants, as well as a collection of ecological data, were done in the west in order to know the adaptability of A. cymosum species. Sulfate crystals were observed in the form of idioblasts in the parenchyma of the cortex, leaves, and stems. Calcium sulfate, altitude, and soil texture factors had a positive effect, but soil salinity and Calcium carbonate factors had a negative effect on the distribution of A. cymosum.IntroductionGypsum soils are one of the most widespread unusual beds in the world (Kayabas, 2020). The gypsum habitats of Iran are important reserves of biodiversity containing exclusive and rare species. However, the exclusivity of plants is often related to morphological, anatomical, and ecological adaptations (Bolukbasi et al., 2016). The species that grow in gypsum soils have different morphological characteristics. The species Bunge Acantholimon cymosum is exclusive to Iran and has been reported in the gypsum soils of the west and northwest of Semnan and Tehran (Assadi, 2005; Rechinger, 1974). The purpose of this study is to investigate the ecological conditions of A. cymosum in the gypsum areas of the west of Semnan and to analyze the relationship between environmental factors and gypsum soils with morphological, anatomical, and micro-morphological features. This research is the first comprehensive study on this exclusive species. Materials and MethodsThe area under study is located in the northern parts of Iran's famous desert called Dasht Kavir between three regions in the west of Semnan. In this regard, maps of the habitats of A. cymosum species in Iran and Semnan were prepared. A sampling of soil and plants, as well as a collection of ecological data, were done in the west of Semnan with an area of 32000 hectares from 55 stations with a distance of 500 meters from each other in order to know the adaptability of A. cymosum species. Also, the contents of gypsum, calcium (Ca), potassium (K), sodium (Na), magnesium (Mg), and calcium carbonate (CaCO3) were measured by standard methods. Spearman's correlation coefficient was used between descriptive variables, and ordination analyses were performed to investigate ecological relationships and soil and topography factors. Funding cymosum species is an exclusive species of Iran. This perennial plant has cushion-shaped bushes with an average diameter of 30 cm, dull green color, white spots or dots, numerous stems with almost long branches, and prickly leaves. The leaves are three-sided, hard, pointed, and rough. The apex is ovate-lanceolate and raised. The inflorescence is cyme, the flowers are 5, continuous and white. Examining the anatomical structure of the leaf blade and inflorescence stem sections of A. cymosum species showed that this species has thick sclerenchyma tissue around the wood and phloem vessels and calcium sulfate crystals in the form of idioblasts in the parenchyma of the leaf and inflorescence stem. The anatomical features of the leaf indicate the existence of dry structures. Due to various factors including the subtropical climate in summer and low rainfall in the central and southern parts, Semnan is a dry region with very little rainfall. The results of the analysis of the environmental factors of the A. cymosum habitats in the study area showed that the average height where this species was found was about 1600 meters above sea level.The soil texture in the areas where this species grows is often with a high percentage of sand (73% on average). The average pH and EC of the soil are 7.58 and 2.62, respectively. The average amount of lime in the vegetative soils of the species is 8% and the amount of gypsum in the vegetative soils of the species is 15%. The average species density was 0.12 m2, species abundance was 65%, and A. cymosum species cover was 23%. Results and Conclusion The term eco-morphological traits and structural characteristics have been used to name the traits of organisms that have a specific adaptive role with environmental conditions (Loidi, 2018). Many plants of specific ecosystems such as chalk and serpentine soils have found micro-morphological adaptations. Escudero and colleagues (2015) pointed out that chalks find certain adaptations in their morphological and ecological features. One of the adaptations found in this study is the presence of crystals in the hairs of the leaves. Previous studies identified gypsum crystals and calcium oxalate inside the leaf cells of gypsum plants (Palacio et al., 2014). Accumulation of gypsum inside the cell vacuole has been proposed as a detoxification strategy for gypsum native species. Although intracellular crystals were not observed in this study, the occurrence of crystals in hairs can also serve as a potential solution for detoxification. In the gypsum regions where this species grows, the dry season is very long and the intensity of drought is high. In order to prevent or reduce water loss during the dry period, plants such as A. cymosum show morphological and anatomical adaptations of their vegetative structure. The results of this study show that A. cymosum has thickened cortex, thickened leaf hairs, increased freshness (with subsequent increase in water accumulation), and a well-developed root system, all of which can be exemplified by a dry rhizome structure. Ecological factors such as soil and climate factors play an important role in the adaptation of this species. Also, a good association was observed between gypsum species in the west of Semnan, and especially between two species, A. cymosum and Astragalus semnanensis. Altitude factors, calcium sulfate, and soil sand texture have a positive effect and soil salinity and lime have a negative effect on the distribution of A. cymosum.
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