Notes and contributions on Corsican flora, XXI.
These notes deal with 123 noteworthy taxa among which 5 are new to the island's flora: Coeloglossum viride, Achillea ageratum × Achillea ligustica, Cerastium fontanum subsp. lucorum, Elatine hexandra and Tamarix dalmatica representing native plants, whereas the 10 following ones: Juncus tenuis, Muscari armeniacum, Pennisetum clandestinum, Mahonia aquifolium, Opuntia crassa, Casuarina cunninghamiana subsp. cunninghamiana, Melia azedarach, Oxalis debilis, Paulownia tomentosa, and Vitis rupestris are introduced subspontaneus species. In other respects, 2 taxa which have been previously misidentified: Cenchrus incertus and Datura innoxia have to be removed from the Corsican flora and have to be replaced by Cenchrus longispinus and Datura wrightii which become 2 new taxa for the island. New localities are given on one hand for 34 taxa considered as "very rare" (RR) out of which 2 (Melomphis arabica and Opuntia monacantha) become "rare" (R), and on the other hand for 31 taxa considered to be "rare" (R) out of which 6 (Asplenium marinum, Leersia oryzoides, Phleum pratense subsp. nodosum, Calystegia silvatica, Calamintha menthifolia and Persicaria decipiens) change their status from "rare" to "not common" (PF). Finally, data published for the 30 remaining taxa (considered "localized" (LOC) or "not common" (PF) taxa) constitute a considerable increase of our knowledge about their distribution. The new sites correspond often to a new sector for the presence of a given taxon. Thirteen of the whole lot of 123 taxa are part of the red list and 36 are xenophytic species. Eleven nomenclatural changes are also given. A distribution map is also provided for Cyperus fuscus, Leontodon saxatilis, Ecballium elaterium and Mercurialis corsica.