In Breginjski kot we conducted a thorough study of populations of two autochthonous taxa from the genus Spiraea. Spiraea decumbens Koch. subsp. decumbens is an Eastern-Alpine endemic subspecies and the southern border of its distribution area is in Slovenia. All of its known localities are in the Breginjski kot and in the Učja Valley. We examined 48 and made a phytosociological inventory of 25 of its localities where we analysed the state of its populations. We identified two new localities in the new quadrant (9746/4) of the Central-European flora mapping grid, at Kozja Peč at the foothills of Mija, where the species occurs on riparian limestone rocks directly along the Nadiža River. This is for now the southwesternmost locality in its entire distribution area, the smallest among those examined in the Breginjski kot and the only locality on limestone. All other populations were found on dolomite sites, the largest was on the locality Plazi at Prekopa above Breginj. Regeneration is mainly vegetative and limited to a small area. Populations are vital and we have not noticed any negative effects of abiotic and biotic factors. Spiraea chamaedryfolia L. subsp. ulmifolia (Scop.) Maxim. is a Southeastern-European taxon whose northwesternmost border of its distribution area is in the Breginjski kot. We examined twelve of its localities in the eastern part of the Mija Mountains and on the rockfall Molida under Mt. Matajur, and conducted a thorough phytosociological inventory of eight localities. The species grows in rocky forests and sometimes establishes itself in the gaps that occur after felling and natural disasters. Its populations are also vital and we detected no major injuries caused by biotic or abiotic factors.
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