2. Local endemism

Ghazanfar (1999) identified "the northern mountains of Oman (including the Musandam mountains) [as] one of the three local centres of endemism in the country" and her Figure 3.3 depicts the high Musandam as an "LCE" separate from the Hajar Mountains generally. On current evidence, however, the "Musandam mountains" (the Ru'us al-Jibal) should probably be excluded from the most rigorous interpretation of that statement. Only four UAE/Oman endemics are found in the Ru'us alJibal and no species has yet been identified that is strictly endemic to the Ru'us al-Jibal.

For the northern Oman mountains as a whole, Ghazanfar (1998b, 1999, 2003) has estimated that approximately 25 plant species are nationally or regionally endemic. That figure would include the mountain regions of the UAE, which has no nationally endemic species. Most of those endemics, according to Ghazanfar, are uncommon and restricted to one or two locations in the mountains, although she includes only five northern mountain endemics in her Red List of the Flora of Oman (Ghazanfar 1999, Table 3.3). She also lists six "common species" from among those endemics, of which only one is found in the Ru'us al-Jibal--Pteropyrum scoparium, which is however acknowledged to be possibly conspecific with P. aucheri of Iran, Afghanistan and Pakistan (Miller & Cope 1996; Ghazanfar 2003). Only four other northern Oman endemics are found within the Ru'us al-Jibal: Desmidorchis arabica, a cactus-like milkweed that is widespread but not common (and is apparently included in Ghazanfar's Red List as Caralluma aucheri); Echinops erinaceus, a spiny thistle, locally common on scree and rubble; Pulicaria edmondsonii, a sloped-welling dwarf shrub that is widespread and locally common; and Stipa mandavillei, a grass found at high elevations that is evidently rare outside the Jebel Akhdar.

Nevertheless, local endemism is high in the Ru'us al-Jibal in the sense that some 75 species, representing approximately 22% of the above-mentioned total of 338 for the Ru'us al-Jibal, are confined, within Eastern Arabia, either exclusively (62 spp.) or very nearly so (13 spp.) to the Ru'us al-Jibal, being absent (or very nearly so) in the Hajar Mountains to the south. A complete list of these locally endemic species is given in Table 3 (see Checklist for additional details).

Among the most common local endemics are a diverse array of distinctive perennials including Artemisia sieberi, Astragalus fasciculifolius, Centaurea wendelboi, Dianthus crinitus, Gladiolus italicus, Ixiolirion tataricum, Jurenia berardioides, Lactuca orientalis, Leopoldia longipes, Moraea sisyrinchium and Prunus arabica, along with a few annuals such as Helianthemum salicifolium and Hippocrepis unisiliquosa. All of the foregoing are higher elevation species. In addition, Convolvulus acanthocladus, one of the three most abundant dwarf shrubs at high elevations in the Ru'us al-Jibal, is a "near" local endemic, having only a very limited distribution in the mountains to the south.

Approximately 80% of the Table 3 species can be found at medium or high elevations (above 700 m) and approximately 75% are found only at those elevations. These numbers emphasise the contribution of higher elevation species to both the diversity and...