Abstract. Delforge, P.- Contribution to the knowledge of the Serapias of the Kyklades (Greece): Serapias carica var. monantha var. nova [Natural. belges 80 (Orchid. 12) (1999): 409-431].  The problematic of the Serapias with one single flower in the Aegean basin is evoked. Research in the Mediterranean basin and examination of the literature show that the presence of numerous individuals or, sometimes, of population of Serapias with one single flower is restricted to some Cycladic islands; that taxon seems heterogeneous. The April-flowering Serapias with one single flower, growing usually with S. carica in Northern Kyklades (Tinos), Central Kyklades (Paros, Antiparos), and Southern Kyklades (Amorgos, Astypalea, Milos, Kimolos, Polyaigos) is not attributable to S. cycladum, a poorly known species, late flowering, described from Andros in 1989. Consequently, this April-flowering Serapias with one single flower is described here as S. carica var. monantha. The presence of S. carica var. monantha is attested in Andros too, but the taxonomy of Serapias with one single flower on that island remains confusing. A list of 40 localities of S. carica prospected from April 1994 to April 1998 in the Kyklades and one distribution map are given as well as of 19 localities from Andros and Tinos which are not attributable with certainty to S. carica var. monantha nor to S. cycladum.

Key-Words: Orchidaceae, Serapias, Serapias carica, Serapias cycladum, Serapias carica var. monantha var. nov. Flora of Greece, flora of Aegean basin, flora of Kyklades.