Sedum ochroleucum Chaix, Crassulacea segnalata nel 1995, come nuova per la Sicilia, da Campo, Pasta, Romano & Troìa

Estratto da Giorn. Bot. It. n. 129 (2): 175 (1995)

NOTES ON THE SPECIES OF SEDUM L. SER. RUPESTRIA BERGER (CRASSULACEAE)
OCCURRING IN SICILY

G. CAMPO (1), S. PASTA (2), S. ROMANO (1) & A. TROIA (3)

(1) Dip. di Scienze Botaniche dell'Università, via Archirafi n. 38 - 90123 Palermo;
(2) Dip. di Biologia Vegetale dell'Università, via G. La Pira n. 4 - 50121 Firenze;
(3) Dip. di Biologia Evol. Sperim. dell'Università, via Irnerio n. 42 - 40126 Bologna.

After our recent finding of populations of Sedum ochroleucum Chaix in Sicily, we have carried out bibliographical researches which have emphasized the controversial opinions, both in national and international Floras, about the occurrence in the island of the species of Sedum L. ser. Rupestria Berger 1930: in fact, the only taxon of this group unanimously reported for the island is S. tenuifolium (Sibth. et Smith) Strobl. In this communication we present some preliminary results of field investigations and of the examination of herbarium specimens (PAL, FI, NAP).
- S. sediforme (Jacq.) Pau, in Actas Mem. Prim. Congr. Nat. Esp. Zaragoza: 246 (1909) (= S. nicaeense sensu Auct. non All. 1785); its presence in Sicily is confirmed: among the species of the series occurring in the island, it is the most common and the most plastic from an ecological point of view, occurring from sea level to 1350 m a.s.l.
- S. rupestre L., Sp. Pl.: 431 (1753) (= S. reflexum L. 1755): we have never found it in the field or in any herbarium specimen (PAL, FI, NAP-GUSS) collected in Sicily and surely referred to this taxon. Therefore, the recent bibliographical records of "S. rupestre" for the island should probably be referred to S. sediforme.
- S. ochroleucum Chaix in Vill., Hist. pl. Dauphiné 1: 325 (1786) (= S. anopetalum DC.): its presence in Sicily is confirmed. GUSSONE was the first to recognise this taxon between Agrigento and Licata and he finally classified it as S. albescens Haw. (Fl. Sicul. Syn. 1, 1842-43). The first record sub S. ochroleucum is found in a vegetational work of BERNHARDT (Webbia 43(2): 291-300, 1989), in which the species is mentioned between Siculiana and Montallegro (AG). PIGNATTI (Flora d'Italia, 1982) and WEBB et al. (in TUTIN et al., Flora Europaea, vol. 1, 2nd ed., 1993) exclude it for Sicily. During our researches in the field we have found it in the following localities, besides Siculiana and Montallegro: Ciminna (PA), Campofranco (CL), Milena (CL), S. Angelo Muxaro (AG), Grotte (AG), Realmonte (AG), Nicosia (EN). On the base of our observations, in Sicily this species grows mainly on the gypsum rocks of the Central and Southern part of the island, between 50 and 600 m a.s.l., under thermomediterranean climatic conditions (average annual rainfall less than 600 mm and average annual temperature above 17° C), preferring however North-facing slopes.
The individuals of the Ciminna population, quite isolated from the other ones, appear sterile and present a triploid citotype (2n=51, Hart 1994, pers. comm.). Montallegro population shows a diploid citotype (2n=34, Hart 1994, pers. comm.). We plan to continue this research to make clear the nomenclatural and taxonomical position of the Sicilian populations of this taxon, as some of their morphological characters (petals nearly patent, sepals glabrous) disagree with the description of the species of Chaix as reported in WEBB et al. 1993.