| Abstract: | A diagnostic key, and new data are provided for seven species of Astragalus sect. Trachycercis , which occur within the area covered by the Flora of Iran. Astragalus brevipedunculatus Ranjbar is described as new, and A. armeniacus Boiss. is reported as new for the flora of Iran. The micromorphology of the seed coat surface of ten Astragalus taxa has been studied by SEM. Considerably different types of sculpturing at species level and similarities between related taxa were observed. In addition, differences between A . sect. Trachycercis and the closely related sections A . sect. Erioceras and A. sect. Wettsteiniana are discussed. Astragalus durandianus , A. pseudoshebarensis and A. shebarensis , which all have strongly inflated pods, are transferred from A . sect. Erioceras to A. sect. Wettsteiniana. Astragalus brevipedunculatus sp. nov., described from a small region near Aras River in Iran, is the only geographically isolated species of the section. Members of the section prefer habitats from coastal dune climates of the Azarbaijan Sharqi Province to the Armenian and Azarbaijan frontiers, although possibly also growing in the adjacent southern parts of Armenia and Azarbaijan. Astragalus brevipedunculatus sp. nov. is the only species of the section in Iran and neighboring countries that has few pairs of leaflets and is completely glabrous. The new species should be considered as a 'Critically Endangered' (CR) following the IUCN criteria. A distribution map for A. brevipedunculatus and A. armeniacus is presented. |
