The Study of the Relationship between Distribution and Anatomical of Astragalus semnanensis

Astragalus L. is from Fabaceae. Astragalus is the largest genus among the flowering plants. Astragalus semnanensis Bornm. & Rech. is from sec. Leucocercisas. A. sect. Leucocercis is one of the few sections of thorny Astragalus that has basifixed hair. Astragalus semnanensis is the only species of this section that is a narrowly endemic one known from a small area in north-central Iran near Semnan. This study focuses on the distribution and anatomy of this plant. The present study was done on gypsum area west of Semnan that is 30,000 hectars in Aftar, Momen Abad, and Lasjerd. Ecological factors such as altitude and physical and chemical characters of soil are studied in this area. For observing the impacts of ecological factors on A.semnanensis used from RDA and CCA of Canoco for windows 4.5. companion plants with A. semnanensis in this area are Acantholimon cymosum, Amygdalus lycioides , etc. Astragalus fridae is another endemic gypsophyte in this area but there is in higher altitude than A. semnanensis. In this area there are many miner and factories for extracting gypsum that damage growing these gypsophytes such as A.semnanensis in this area.