Taxonomical remarks on Trifolium savianum Guss. and its relationship with T. uniflorum L.

Abstract

In the frame of investigations on endemic or rare taxa of the Sicilian flora, Trifolium savianum Guss., a misappreciated species occurring in a small area of Peloritani mountains (NE Sicily) is examined. According to literature data, the species has been considered as a synonym of T. uniflorum L. (Lojacono, 1891; Zohary, 1969; Jafri, 1980; Zohary & Heller, 1984; Greuter, 1989), as a variety (Gibelli & Belli, 1892; Vierhapper, 1919; Fiori, 1925) or as a subspecies of the aforesaid species (Nyman, 1878; Coombe, 1968; Tutin et al., 1968; Pignatti, 1982). The analysis of morphological features, carried out on herbarium and living matherial, has highlighted that T. savianum can be considered as a distinct species, which differs from T. uniflorum in several characters regarding leaves, flowers and fruits. In particulerm T. savianum has the lower surface of leaflets opaque, feebly pubescent, with 7-12 teeth 0.3-0.5 mm long on each side, calyx 12-15 mm long 3-4.5 mm in diameter, with teeth curved up to 2.6 mm wide at the basis, corolla purplish, standard with limb elliptic slightly retuse, claw 3.5-4 mm wide, anthers linear elliptical 1.4 mm long, ovary with hairs 0.5-0.8 mm long, fruiting pedicels markedly thickened and recurved, while T. uniflorum is characterized by the lower surface of leaflets shiny, glabrous or subglabrous with 15-22 teeth 0.15-0.25 mm long on each side, calyx 5-11 mm long, 2-3 mm in diameter, with teeth erect up to 2 mm wide at the basis, corolla whitish to pink, standard with limb obovate-spathulate retuse-emarginate, claw 2.5 mm wide, anthers elliptical 0.9 mm long, ovary with hairs 0.2-0.35 mm long, fruiting pedicels unthickened and not very recurved or sometimes twisted. As concerns the chorology and ecology, T. savianum is localized on mountain places near Mandanici (NE Sicily) at 900-1200 m of altitude, where it is a member of a perennial pulvinate community colonizing schistose sunny slopes. It was recorded also from Scilla (SW Calabria) by Pasquale (1907) but quite surely he was wrong. T. uniflorum is widespread in the E Mediterranean area, where it grows on coastal and inland phrygana or garrigues occurring on various substrata. According to Vierhapper (l.c.) and Hossain (1961), T. uniflorum is represented by several very variable populations often regarded as distinct taxa differentiated at specific, subspecific and variety rank, that may deserve a further thorough analysis. Therefore on the basis of morphological, ecological and chorological data, T. savianum can be considered a Sicilian endemic arisen from a very old geographic isolation from the eastern populations of T. uniflorum.