A New Species of Ziziphus Mill. (Rhamnaceae) from Oman

Abstract

Four native species of Ziziphus (Rhamnaceae) have hitherto been recorded from the Arabian Peninsula (e.g. Al-Hubaishi & Miuller-Hohenstein 1984, Collenette 1984, Miller & Morris 1988, Mandaville 1990, Ghazanfar 1992, Wood 1997; also specimens in K). Of the two species which are trees, Z. spina-christi (L.) Desf. is the most widespread within this region, occurring from sea level to c. 2500 m (a collection from Oman at K, Insall s.n., Dec. 1978, Hail al Kabir, identified as Z. mauritiana Lam., is most probably the cultivated form of Z. spina-christi), while Z. mucronata Willd. occurs only in the mountains of western Saudi Arabia between c. 1000 1500 m. Of the two shrubby species, Z. nummularia (Burm. f.) Wight & Arn. occurs in the eastern part of the region, including the northern edge of the Wahiba Sands in Oman, and Z. leucodermis (Baker) O. Schwartz is restricted to south eastern Yemen and, in Oman, to the adjacent drier regions of the southern province of Dhofar and to the southern part of the central limestone plateau, the Jiddat al Harasis. Here we describe a new taxon, locally called qusum (qasam in Mandaville 1978), from the Hajar Mountains of northern Oman.