Notes on the distribution, ecology and conservation status of two very rare sedges (Carex, Cyperaceae) rediscovered in Sicily (Italy)

New data on the geographical distribution and ecology of two rare taxa of Carex collected in the area of the Nebrodi Mountains (Sicily) are provided; the Sicilian populations of both taxa are at the border of their respective ranges, and their regional distribution is still poorly known. The new population of Carex x boenninghausiana reported here confirms the presence of this hybrid in Sicily, but at the same time it represents the only known population currently occurring in Italy; in fact, the other - so far only - known Italian population is considered extinct. The second report concerns Carex grioletii, recently considered doubtful for the Sicilian flora, whose new population here reported is the only confirmed and currently present population in the island; the assessment of extinction risk and conservation status, carried out at regional (Sicilian) level according to the IUCN criteria for the latter taxon, showed that it is Critically Endangered (CR).