The first two sources refer to the major phytogeographical districts only, whereas the grass monograph uses a detailed subdivision. Because of this, the assignment of some grasses that are recorded for the Isthmic Desert remains problematic and should be added either to the Sinai district or to the Eastern Desert. The number of these grass species is low, however, and therefore has no significant influence on the calculations . In each phytogeographical district, plants have been divided into three classes. The second class shows the number of species also recorded from the Eastern Desert and Red Sea coastal strip. For the Eastern Desert this second class refers only to the number of plants also found in the Red Sea coastal plain, and for the Red Sea coastal plain the case is vice versa. The third class represents plant species found in the concerning region and other regions but excluding the Eastern Desert and the Red Sea coastal strip. Four phytogeographical districts are characterized by a reasonable number of indigenous plants, which give them their individual status: the Mediterranean coastal strip , the Nile region , the Gebel Elba , and the Sinai . In the other four districts, these percentages vary between 2 to 5 percent, indicating that on a presence/absence analysis the flora in these districts does not differ much. The flora of the Sinai comprises no less than 61 percent of the Egyptian flora. This high percentage, together with the rather high number of indigenous plant species,blueberry pot size reflects the variety of habitats in this district and may also justify a further subdivision of the Sinai phytogeographical district as has been published elsewhere .
The Mediterranean area, where plant growth is favored by the relatively large annual precipitation and mild temperatures in winter and summer, represents 49 percent of the Egyptian flora. Although the Egyptian deserts are characterized as hot and hyperarid, the desert flora is quite rich and diverse in plant numbers. Remarkably, the number of species in the Western Desert is considerably smaller than that of the Eastern Desert. With 39 percent, the number of species in the mountainous area of the Eastern Desert is more than twice as much as that of the Western Desert and almost equals the species richness of the Nile Valley and Delta. Even the number of species recorded for the small coastal plain bordering the Red Sea is considerable: 15 percent. The proximity to the sea, the variation in environmental conditions, and the effective concentration of rainwater in the wadi system seem to be favorable factors in this respect. The flora of the coastal plain is, for the most part, also present in the Red Sea mountains. At least 800 plant species occur in both these landscapes. Of these species, 32 percent is present in both areas and only 3 percent is unique for the coastal plain . The small percentage that is specific for the coastal plain can be attributed to the presence of salt marshes, an ecosystem that is characterized by its limited number of species. Certain species of the flora of the Red Sea mountains and the coastal plain are also present in the other phytogeographical districts. This is also true for the Gebel Elba area, where the Sudanian flora penetrates into the north. A group of large mountains, including the Gebel Elba, is located near the sea and causes much orographic rain. This is especially true for the north and northeast flanks, where even several moss species and ferns are quite abundant on the higher latitudes. A total of 443 different vascular plant species have been recorded for the Elba mountains, and its botanical richness is in marked contrast with that of the mountains north of this area. The barren Red Sea mountains north of lat 23° N have only a limited plant cover.
On rock surfaces where some soil has accumulated and in the many small affluents through which the runoff water drains into the main wadi beds, short-lived plants are present in particular. Most of the vegetation is, however, concentrated in the wadi branches and consists of both ephemeral and perennial vegetation. The number of flowering plants in a particular wadi is estimated by Schweinfurth at 60 to 100 species. The vegetation in these wadis also penetrates the coastal plain close to the Red Sea, where it is finally replaced by a salt-marsh vegetation. These salt marshes can be quite small, as is the case in the delta of Wadi Gimal, or may penetrate inland for several kilometers. Plant growth in wadis is determined by the catchment area as well as the thickness and composition of the wadi filling. Small, shallow wadis are dominated by drought-tolerant plant species. Broad and deep wadi beds on the other hand, which are filled with sand deposits and are fed by a large mountainous area, act as natural reservoirs for large quantities of water. In such deep wadis, only the upper layers dry up completely. Remarkably, perennials with long roots can reach the deep water table and are able to survive in these restricted environments year round. Trees, such as Acacia tortilis, are mainly found in the transitional zone between the elevated terraces and the central part of the wadis and along the convex sides as this fringe optimizes the availability of groundwater and protection against erosive flood waters. Smaller perennial species, such as Chrozophora plicata and Cornulaca monacantha, that have successfully established themselves in the central part of the wadi are often badly damaged by previous floodings. The thick, woody stems indicate that such specimens have a considerable age. The terraces of the coastal plain support almost no vegetation: only ephemeral vegetation is present, this being dependent on rainfall.To facilitate a better interpretation of the sub-fossil record of wild plant species from Berenike and Shenshef, a small-scale inventory of the recent natural vegetation has been made.
This inventory of the vegetation is based on plants collected around Berenike, Kalalat, Khesm Umm Kabu, Hitan Rayan, Shenshef, and Qariya Mustafa ‘Amr Gama and on the description of 16 relevés located at Berenike, Kalalat, and Shenshef . A relevé is a vegetation sample which is deliberately chosen as being a uniform and representative sample of the plant community being described . It is stressed that, apart from the descriptions of the relevés, these inventories are biased by differences in the duration of the visits paid to these sites. A short visit will certainly result in an incomplete inventory, as many plants are relatively small in size due to an adaptation to moisture shortage in particular and may easily be overlooked if they are present in low frequencies. Gisekia pharnaceoides may serve as an example. This plant species is the only member of the Gisekiaceae in Egypt and is recorded for the Eastern Desert and the Gebel Elba area . Several specimens of this prostrate annual were found around Fort Kalalat and measured sometimes hardly more than 1 cm , whereas in the wadis of Gebel Elba this plant species is considerably larger. Under more favorable conditions, the stems may reach a length of 10 to 40 cm . The possibility that this particular plant species has been overlooked at other sites cannot be ruled out. The Roman settlements that have been less-intensively investigated are Khesm Umm Kabu, Hitan Rayan, and Qariya Mustafa ‘Amr Gama. The first two settlements were visited twice and the last one only once. In all of these locations, most of the plants that have been recorded originate from the wadi branches. Berenike, Shenshef, and Kalalat have been visited during all excavation seasons. Berenike was visited during the excavation seasons from 1994 to 1998, making it possible to look at the vegetation from late December until early March. The inventory covers the salt-marsh vegetation and the vegetation in the branches of Wadi Mandit west of Berenike and Wadi Umm el-Mandit south of the site. The inventory of the vegetation in the surroundings of the watering station Kalalat is based on the plant species that grows inside the fort and on the sand that has accumulated along the outside of the external walls. Additionally,plant raspberry in container plants from the wadi branches around the watering station and on the fl at coastal plain were listed. A thorough study of the plants around Shenshef could be made because one of the visits lasted for two weeks and took place after heavy rainfalls. Plants were collected from the main wadi branch and its affluents, from the slopes of the mountains, and from the terraces occupied by the former settlement . The completeness of the inventory is also affected by the time of the year. Although all sites were visited during the excavation seasons, which lasted from late December to early March, and the life cycle of most annuals coincide with this relatively mild part of the year—due to lower temperatures and availability of water— plant species may still have been missed because they had not yet germinated or were already withered. Identification of very young plants, lacking characteristic features of flowers and fruits was, however, still possible in most cases by using leaf characteristics and by looking at the germinated seed or fruit still attached to the root, which was easily gathered from the loose sand.
This last method proved to be successful especially with respect to grasses with a resistant fruit coat, such as Centropodia forsskalii, Aristida spp., and Stipagrostis spp. All Egyptian members of both last genera can easily be identified to the level of species on the basis of their fruit characteristics . Some other young plants lacked such characteristic features, such as Fagonia spp., and could therefore not be identified beyond the genus level. Finally, the sampling is further distorted by differences in the vegetation between years, which in turn are related to variations in precipitation. This seasonal phenology is witnessed in nonsaline ecosystems of the deserts . Some plant species, such as Arnebia hispidissima and Zilla spinosa, were observed every season, though in varying density, whereas others, such as Senna italica and Cleome amblyocarpa, were infrequently present in the same wadi branches.The plant composition in the relevés is summarized in Table 2.1. Although the size of the relevés is relatively small for a desert environment, the number of species is surprisingly high. It varies from 5 to 19 with a mean value of 13. Also the plant cover can be reasonable high as it varies from 10 percent to 85 percent. It has to be realized, however, that these inventories were made after heavy rainfall, resulting in exceptionally rich vegetation, which found its expression in both plant cover and in the proportion of ephemeral species. Ephemeral species have a short life cycle and need water only during a part of the year. The distinction between ephemerals and perennials is not exclusive, as some perennials such as Zilla spinosa, Pulicaria undulata, Farsetia ramosissima, Citrullus colocynthis, and Trichodesma africanum can also behave as ephemerals if there is a shortage of water. Common ephemeral species are Zygophyllum simplex, Lotononis platycarpa, Triraphis pumilio, Eragrostis ciliaris, Arnebia hispidissima, and Astragalus vogelii. Zilla spinosa is a perennial species that is present in most relevés, though mostly at a young stage of development as perennial species tend to develop more slowly. Z. spinosa is absent in the vicinity of the sea. The diversity of grasses is striking. A total of 16 species has been recorded, of which 15 grasses are also present in the relevés. With the exception of Rostraria pumila, which grows as a small grass in a wadi branch near the watering station Kalalat, all these grasses are C4-species. Such species are adapted to arid conditions by a different photosynthetic pathway and a regulation mechanism that minimizes evaporation. The distribution of the C4-grass species seems to be influenced primarily by temperature . In the southern part of the Eastern Desert C4-grasses make up 81 percent of the species, in the Red Sea coastal zone 93 percent, and in the southerly located Gebel Elba area even 95 percent. The high proportion of C4-grass species in the vicinity of the Roman installations corresponds quite well with these percentages. Most grass species become reasonably tall and produce a substantial amount of biomass for grazing, such as Aristida spp, Stipagrostis spp., Dichanthium foveolatum, Cenchrus ciliarus, and Panicum turgidum. In years with limited or no autumn rain, those species are heavily grazed .