Tài liệu Thực vật chí jizan

Flora of Jizan Region AR-17-7 Final Report Vol.- 1 By Principal Investigator Prof. Ahmed H. Alfarhan Herbarium, Dept. of Botany & Microbiology, College of Science, King Saud University, Riyadh. Co-investigators Prof. Turki Ali Al-Turki Natural Resources and Environmental Research Institute, King Abdulaziz City for Science and Technology, Riyadh. Prof. Abdullah Yahya Basahy Community College, King Khalid University, Jizan. Supported by King Abdulaziz City for Science and Technology (KACST) 2005 2 Contents. I. Preface 4 II. Acknowledgements 6 III. Introduction 7 IV. A. Topography and Vegetation 7 B. Climate 23 C. History of Plant Collection 26 D. Plan of the Flora 27 E. A brief account of the flora of Jizan Province 28 F. Cultivated plants from Jizan Province 30 G. Weeds of Jizan Province 32 H. Threat facing the flora of the region 33 I. Regional Endemic plants 37 Systematic Account of the flora 38 1. Pteridophytes 38 2. Gymnosperms 44 3. Angiosperms-Dicots 46 4. Angiosperms-Monocots 428 V. Gazatteer 506 VI. References 507 VII. List of Illustrations 510 VIII. Vernacular Names 516 IX. 523 Index of species and families. 3 I. Preface The identification of wild plants from Saudi Arabia was difficult in the past few decades particularly in 1980's and in the beginning of 1990's primarily due to the lack of a well written Flora. Although a consolidated work of the plants of Saudi Arabia (various editions of ‘Flora of Saudi Arabia’ published from 1974 to 1990) by Prof. Migahid (King Saud University, Riyadh) was available in those days, the book contained only half of the plants that are known today and moreover, a considerable number of names and photographs given in the text were, to a certain extent, confusing and erroneous or sometimes even misleading. The need for an updated Flora was therefore inevitable for both botanists and students of this region. During the last two or three decades, plant collections in the Arabian Peninsula have been intensified with the active support and collaboration of various Ministries, Universities and Organizations; and as a result of such intensive and extensive plant explorations, the number of wild species from Saudi Arabia has been increased from an approximately 1500 species to 2243 species. Among these a significant number of species are reported from the Jizan Province, particularly from the high altitude regions, such as Jabal Fayfa, Wadi Lejib, Jabal Qahar, etc. Although the regions in and around Jizan were famous for their traditional agricultural lands and centuries old houses on the mountain slopes, the area was botanically less known to the outside world. One of the reasons was, perhaps, due to the lack of motorable roads along the mountain range or most of the botanists/collectors were residing in major cities far away from the region. Although several expeditions were conducted along the inhospitable tracts of the mountains of southwestern region, particularly in the Jizan Province ever since the period of Forsskal in the eighteeth century, botanists in Arabian Peninsula had a strong feeling that a thorough exploration in and around Jizan would help in adding several species to the flora of Saudi Arabia as the region borders with one of the botanically rich regions like Yemen. We, in 1998, have realized the importance of studying the flora of Jizan Region and submitted a proposal to the Directorate for Research Grant Programme, King Abdulaziz City for Science and Technology (KACST). Fortunately the proposal was approved by the authorities in the same year and the concerned studies for the write up of a Flora was initiated in 1999. 4 The work of a provincial flora of southern Saudi Arabia, such as this one, is first of its kind in the Kingdom. The value of such a work is, therefore, helpful in knowing the distribution range of several species in the region. An analysis on the results obtained at the end of the study revealed that a significant number of species were reported for the first time from Jizan region. Southwestern region, particularly Jizan Province is important for many centuries as far as the vegetation is concerned because of the region’s close proximity with several North Eastern countries in Africa, particularly Ethiopia which is one of the Vavilov’s centres of origin of cultivated plants. Plants such as Coffea arabica, Sorghum bicolor, etc. have been cultivated in this region for many centuries and it is believed that some of the wild varieties of these genera are important for plant breeding purposes. The fruits, seeds and other propagules of several wild and cultivated plants of this region are also a good source material for gene banks. In short, this work provides the very basic data regarding plant wealth of Jizan Region and helps students of Botany to open up research in various taxa. The purpose of the Flora of Jizan Project stands for fulfilling three main objectives. The foremost objective was to write up a Flora of Jizan Province. Secondly to enrich the Herbarium (KSU) at the Botany & Microbiology Department, King Saud University with specimens from the study area, and thirdly to sort out the confusion pertaining to the nomenclature of some of the confused taxa and also to add more species or genera to the existing floristic list. Seven reports were submitted during the project period, each containing the description of an average 150 species. This is the final report of the project (AR17-7) funded by the King Addulaziz City for Science and Technology (KACST). This report deals with 850 species of Vascular plants which are wholly indigenous or naturalised. Exhaustive keys to taxa like genera and species have been provided for easy determination. Key to the families is avoided in this work. Readers who wish to look at the key to the families can follow the key given in the Flora of the Kingdom of Saudi Arabia, Vol. 1., pp 16-31. (Alfarhan & J. Thomas in Chaudhary, S. 1999, Ministry of Agriculture and Water, Riyadh). 5 II. Acknowledgements The work of this project has started in 1999 and continued for about five years. During this period, a considerable number of specimens have been collected and deposited in the Herbarium (KSU) at King Saud University. Apart from the new collections, all previous collections from Jizan Province deposited in various Herbaria in Riyadh have also been incorporated while writing the final report of this project. All these efforts were achieved by the active and dedicative backing of a number of people. Though it is difficult to mention all of them, it would be inappropriate ignore the following names. We are highly indebeted to the Director at the General Directorate for Research Grant Programme, King Abdulaziz City for Science and Technology (KACST) for moral and material support, which were indeed a great boost in carrying out and completing this work. We are also thankful to all concerned members at the Office of the Vice President, Graduate Studies and Research, King Saud University for their quick and sincere efforts in forwarding the files and reports to KACST. We are also grateful to the referees of this project, whose timely suggestions and comments during the course of this research had helped us to improve the contents of the periodical reports and the overall nature of our research work. We sincerely thank Mr. Jacob Thomas (Curator, Herbarium, KSU) for the help he has extended to us during the course of this research, without which a work of this kind would not have been completed even now. We also thank other staff of this project paticularly Dr. Mathew Varghese (Research Assistant) and the scientific artists, Mr. M.Y. Saleem and Mr. Pradeep Kumar who spent 1-2 years during the project-period,. Dr. Mathew and Dr. Swarupanandan (KACST) were part of the expedition teams to the study-area on several occasions. The paintings of the plants by the artists are extremely good and appreciable which, in fact, have helped us to improve the overall quality of this report. Their contributions to this project are highly laudable. We also extend our gratitude to Mr. Saleh Al-Shaye (Herbarium, KSU) and to Dr. A.E. Shanavas Khan (KACST) for their help in the preparation of a few interim reports. Dr. S. Chaudhary (National Herbarium, RIY) was helpful on many occasions. His timely advice and suggestions helped us to sort out the confusion pertaining to the nomenclature of several specimens. Finally we thank Mr. Mohammed Mateen for typing several interim reports. 6 III. Introduction The Jizan Province is situated in the south-western part of Saudi Arabia. The study-area except Farasan Islands is located between 160 20` N to 170 40` N and 410 55` E to 430 20` E. (Figs.1 & 4). The southern region of the study area borders with the north-western frontier regions of Yemen while its northern and eastern sides border with Ash-Shuqaiq town and the eastern slopes of Fayfa Mountains respectively. The region has about 260 km long coastal area on the western side, stretching from AlMuwassam in the south to Ash Shuqaiq in the north. There are a few islands (Farasan Islands) in the Red Sea, 40 kms off the Jizan coast. It is a conglomeration of several big and small islands, ranging from 369 sq. kms to less than 5 sq. kms. The study area is part of the Arabian shield, which is covered by Tertiary volcanic rocks. During the Precambrian age, Jizan Province was part of the African continent. As a result of tectonic movement, the quadrangular mass of Arabia separarted along the Red Sea and occupied a position between Africa and the rest of Asia. The vegetation of this region is therefore closely related to that of East Africa. Two phytogeographical regions are present within the study area, viz. the Somali-Masai regional centre of endemism and Afro-Montane archipelago-like regional centre of endemism. The Jizan region can be broadly divided into Tihama, the Escarpments and the Farasan Islands. The first two regions were part of the oldest agricultural centres of the Arabian Peninsula and composed of wadis, mountains and plateaus. In ancient times, these areas were regarded as the gateway for both crop plants and early travellers from the African and Asian countries. Although the economic boom in the Kingdom from crude oil has diminished importance of Jizan Region, the well maintained agricultural terraces along the slopes of southern Hijaz Mountains still supported the growth of a wide range of cash crops including Sorgo, Coffee, Millets, etc. The area contains a significant proportion of species of the flora of Saudi Arabia, including several endemic and rare species. As the area is located in the south-western tip of the country, the rich and varied flora present in the mountains have a close proximity with the floras of Yemen and East Africa. A. Topography and vegetation A.1. Tihama This area lies between the Red Sea and the Escarpments, with a maximum width of 80 km in the west-east direction and covers about 24, 000 sq. km. The evolution of Tihama is believed to be started in Oligocene and continued to recent geologic times. The whole area can be divided into: shoreline, salt pans, sand-dunes & plains and wadis a. Shore line. The entire coastal line of Jizan Region, stretching about 260 km in the north-south direction, is more or less fringed with many inlets and creeks ("Mersas" or Khawrs"). The shores are sloping gently towards the sea, paving for a wider horizontal tidal belt with no erosion. On the basis of the steepness and soil compositions, different zones of plant communities have been observed along the shore-line. In Ras-Qarn, where the inter tidal belt is sloping gently and the bottom area is sandy and rocky, the community 7 is dominated by sea grasses whereas in Midaya, the community is dominated by Algae because of a steeper and muddy shore-line. Patches of Avicennia marina are common in the shallow waters of the creeks and inlets. These mangrove-plants along with their pneumatophores serve as shelters for many larvae of the sea. Most of the mangrove stands are located near the openings of wadis. Thick deposits of alluvium and other sediments (which are brought in by flash floods from the escarpments) are present in these estauries. The extent and magnitude of the growth of Avicennia marina stands varies from area to area. The Avicinnea stands of Khawr Abu Saba and Madaya were reported to be the longest (45 and 30 km respectively) while that of Al-Sehee was only 2 km. Most areas of open coast is characterised by elevated Pleistocene reef flats. Large colonies of sea grasses (Halodule univervis, Halophila ovalis) can be observed along the fringes of the reefs in the shallow waters. The surface, on which these grasses grow, varies from almost pure fine sand to coarse sand with shell debris. 8 Fig. 1. Map of Jizan Province Alluvial soil that comes in along with rainwater, accumulates in the protected areas such as inlets and creeks, and provides a substratum suitable for mangrove vegetation. Khawr Abu Saba, Ras Qarn, Midaya, Besari, Al-Sehee, etc. are some of the areas that provide a habitat for the luxurious growth of Avicennia marina (Forssk.) Vierh. Soils in these areas are generally blackish-brown or dark brown in colour, indicating the presence of high organic matter. Although mangroves can be seen in the entire coastal region of Jizan province, the longest concentrations are in Khawr Abu Saba (45 km) and Midaya (30 km), while the widest areas are in Midaya and Besari with an average width of 150m. Mangrove population in the mainland consists of a monospecific population (Avicennia marina) whereas in Farasan Islands and in one or two pockets along the Red Sea coast, Avicennia marina can be seen growing along with another mangrove, Rhizophora mucronata Lam. Fig. 2. Tihama plains. Vegetation dominated by Leptadenia pyrotechnica and Acacia tortilis The presence of sea-weeds is the most characteristics of all sea coasts, including the coast of Jizan. Approximately 34 species belonging to four categories (Green, Red, Brown and Blue-Green) were recorded from the study area. However, the sea grasses are apparently dominating over algae (sea weeds) in most of the sub-littoral areas, particularly in regions around Ras Qarn. A total of six species (Cymodoca rotundata, Enhalus acoroides, Halodule australis (=univervis), Halophila ovalis, H. stipulaceae and Thalassia hemprichii) are reported from the regions between Muwassam and Ras Al-Tarfa. These sea grasses are usually seen in areas ranging from deep to shallow waters. Enhalus acoroides is always seen in deep waters (c.1-1.5 m) followed by Thalassia hemprichii, whereas all other species occur in less deeper waters. All these species can be observed in between 1 m to 300 m away from the sea-shore. Nevertheless, the distribution of sea grasses is not uniform in all places. For example, in Midaya, Muwassam, etc, the occurrence of these plants is not so prominent because of 9 high water turbidity. b. Salt pans (Sabkhas) The sea-grass substratum and mangrove-fringe are backed by a more or less unbroken narrow stripe of salty areas which extend the entire western side of the study area. In areas where there are no wadi systems and no accumulation of alluvial soils, the salt pans gradually descent towards the shallow sea. However, the drainage in these sabkhas is very poor and therefore water accumulate on the surface of these pans, forcing the salt to precipitate on the substratum. The vegetation in such habitats is dominated by Suaeda monoica, Halopeplis perfoliata, Sporobolus spicatus, Aeluropus lagopoides, Cressa cretica, Tamarix nilotica, Zygophyllum simplex, Desmostachya bipinnata, Cyperus conglomeratus, etc. c. Sand dunes and plains Dunes and plains constitute some of the major land-forms in Tihama. Major wadis and their tributaries dissect through the dune formations and end in the Red Sea. Dunes are usually formed by the deposition of silt brought in by the flash floods and subsequent piling up of sand by wind. During rainy days flash floods often over flows the low banks of the wadis and spill over a wide area. Suaeda monoica, apart from its presence in sabkhas, also forms small stands on the dunes. Other dominating plants include: Leptadenia pyrotechnica, Panicum turgidum, Pennisetum divisum, Diptergium glaucum, Tephrosia purpurea, etc. The field observations indicated that most of the areas within the open plains are appear to be barren. Since this part of Tihama is very dry, the density and vigour of plant growth are mainly controlled by the availability of water. The vegetation in these plains is represented by both trees and shrubs. The important plants are: Acacia tortilis, Ziziphus spina-christi, Leptadenia pyrotechnica, Indigofera spinosa, Aerva javanica, Senna italica, Calotropis procera and Capparis decidua. Among the herbs, Fagonia indica, Blepharis ciliaris, etc show a greater representation in dry plains. Muwassam (160 20' N, 420 45' E), the southern tip of the study area, bordering Yemen, is a coastal area with a few plants of xerophytic and halophytic adaptations. Avicennia marina, which is dominating in most parts of the shoreline, is in a highly grazed state in the mainland area of Muwassam, whereas the mangrove-vegetation is highly intact in small islets. Close to the sea-shores but away from the sea-water, plants like Suaeda monoica, Zygophyllum coccineum (Z. boulosii auct Hadidi), Z. simplex, Cressa cretica, Aeluropus lagopoides, etc, are common in many places. As usual, ephemerals constitute the bulk of the vegetation in inlands. On the way to Samtah and Muwassam, the most dominant plant community along the sides of the highway is the Salvadora persica, which often forms dense thickets intermixed with Acacia ehrenbergiana. Undulating sand dunes occupies in a relatively small area. These sand dunes are less mobile and are often without plants. However, Leptadenia pyrotechnica, Acacia ehrenbergiana, Tamarix nilotica are some of the species colonizing on these dunes. The vegetation in the entire southern region, which is close to the Yemen-border, is more or less sparse. Yet, there is a gradual increase in the density and abundance of plants from the seacoast to inlands. Large thickets of Salvadora persica are prominent in many parts of Madaya, Samtah and At-Tuwal. As mentioned earlier, the other dominant species in these regions are Calotropis procera, Acacia ehrenbergiana, Leptadenia pyrotechnica, Suaeda monoica, etc. In and around the regions of Madaya, sand accumulates at the base of Leptadenia pyrotechnica and Acacia ehrenbergiana. Tamarix aphylla, T. nilotica and Ziziphus spina-christi along with Tephrosia purpurea, Calotropis procera, Aerva javanica, Abutilon bidentatum, etc. takes 10 refuge along the banks and on raised beds of the wadis. 11 Fig. 3. Geological map Jizan plain. 12 Fig. 4. Topography of Jizan Province d. Wadis Although the slopes from the foot-hills are gradual, there are areas where small gullies develop prior to the formation of large water courses. There are about fifteen wadis, crossing Tihama of Jizan Region and heading in a seaward direction. Among these wadis, Itwed, Baysh, Dhamad, Jizan and Khulab are considered important. These wadis account for a mean annual run off rate in the Red Sea of 7.4 m3/Sec. The wadis are generally dry for the whole year or for successive years. However, occasional spates develop during rainy days. These flash floods often destroy the riparian vegetation. The vegetation in the wadis, near the foot-hills is luxuriant 13 whereas it is sparse as the wadis approach nearer to the sea. Near the foot-hills, where the wadis originate, the vegetation is dominated by Acacia ehrenbergiana, Salvadora persica, Dobera glabra, Delonix elata, Tamarindus indica, Berchemia discolor, Imperata cylindrica, etc. Along the wadis, small lagoons or stagnant water support the vegetation of Typha domingensis, Cyperus laevigatus, etc. Vegetation in wadis of Central Tihama is more scattered except in large depressions where it appears to be more pronounced. Dominating plants of this area include: Hyphaene thebaica, Phoenix dactylifera, Desmostachya bipinnata, Tamarix nilotica, Abutilon bidentatum, Senna alexandrina, Acacia ehrenbergiana, etc. Climbers like Pentatropis nivalis, Cocculus pendulus, Zahneria anomala, etc often grow on trees like Acacia spp. and Tamarix nilotica. Although wadis support the vegetation of a considerable number of mesophytes, patches of xerophytic communities comprising Aloe spp. Desmidorchis retrospiciens and Cissus rotundifolius show their presence near the vicinity of the foothills. Flash floods originate from the deep gorges of the western slope and join with the upper tributaries of the main wadi systems. Wadis are part of a 20-40 km or so long water courses, stretching from the foot-hills of Fayfa Mountains to the Red Sea. Wadi beds are generally dry with deposits of sand and silt. Severe soil erosions were observed in many places of the main water path except in areas of dense vegetation where the plant roots firmly bind the silt together. Vegetation of these silt pans are dominated by Acacia tortilis, Acacia ehrenbergiana, Salvadora persica, Desmostachya bipinnata, Tamarix nilotica, Senna alexandrina and Abutilon bidentatum. The silt pans of the wadis, in certain areas, extend into broad plains, thus merging with the sand dune plains of the coastal areas. Vegetation of such areas is dominated by Ziziphus spinachristi, Leptadenia pyrotechnica, Hyphaene thebaica, etc. Ground cover in the entire wadi area is sparse. However, some of the widely distributed species are Glinus lotoides, Amaranthus graecizans, Boerhavia difffusa, Zaleya pentandra, Pluchea dioscoridis, Cucumis prophetarum and Emex spinosa. Wadi Tashar and wadi Kawbah, the border regions near Yemen frontier, are more favorable for plant growth as most of the silty regions of the wadi are wet due to stagnant water. Dense vegetation comprising Saccharum spontanem, Tamarix spp., Acacia ehrenbergiana, Indigofera oblongifolia, and Lawsonia inermis can be seen along the banks whereas Panicum turgidum, Blepharis ciliaris, Aerva lanata, Lippia nodiflora, Eclipta alba, Senra incana, etc. are dominating on the dry surfaces and near the stagnant waters of the wadis. The hilly areas are generally dry and hot due to the lack of any precipitation. The perennial components, other than the succulents like Euphorbia triaculeata, Desmidorchis retrospiciens, etc. and trees like Dobera glabra, Acacia ehrenbergiana and A. nubica were highly grazed and look-like club formations. Characteristic perennial components include: Cadaba rotundifolia, Commiphora quadricincta, Jatropha pelargoinifolia and grasses such as Cenchrus pennisetiformis, Panicum turgidum, etc. Another important, rather interesting area visited by the team during their exploration was Wadi Lejib (170 40' N, 420 55' E). It is about 100 km NE of Baysh and situated in the middle of two steep mountains. It is a 20 km long narrow gorge with numerous small and large boulders spreading along the wadi beds. Vegetation along the mountain summit is dominated by Olea europea, Ficus cordata ssp. salicifolia, Clutia reichardiana, Caralluma spp., etc. The slopes leading to the gorge is sparsely vegetated with a few trees like Mimusops laurifolia and14 Ziziphus spina-christi. The major tree components in wadi Lejib include: Nuxia oppositifolia, Ficus vasta, Grewia velutina, Breonadia salicina, Cordia sinensis, Phoenix reclinata, Trichillea emetica, Terminalia brownii, Cadia purpurea, etc. At least a few plants like Epipactis veratrifolia, Periploca visciformis, Pisonia aculeate etc, are also collected from these gorges which, in Saudi Arabia, are appear to be confined to the wadi Lejib only . Although there are a lot of recreational activities, like camping, take place at the mouth of the gorge, the vegetaion, to a certain extent, is less altered by external influence and therefore, despite the decline of the population of many trees such as Mimusops laurifolia, Breonadia salicina, etc., in other parts of the country, the populations of these trees and many other endangered plants are thriving well in Wadi Lejib (Lejib Gorge). Fig. 5 . Major wadis in the study area. 15 1. 2. 3. 4. Fig. 6. Vegetation Map of the Jizan Province 16 Acokanthera-Rumex nervous community Juniperus procera community Xeromorphic scrub community Acacia ehrenbergiana-Commiphora community 5. Avicennia marina community 6. Rhizophora-Avicinnia community 7. Zygophyllum coccineum-Cressa creticaAeluropus community 8. Limonium axillare-Zygophyllum community 9. Acacia- Leptadenia community 10. Suaeda monoica community 11. Acacia ehrenbergiana-Salvadora community 12. Acacia ehrebergiana-Acacia tortilis community 13. Acacia-Dipterygium-Ziziphus community 14. Panicum turgidum-Pennisetum divisum community 15. Acaica tortilis-Salvadora-Leptadenia community 16. Panicum-Leptadenia community 17. Suaeda monoica-Leptadenia community 18. Acacia tortilis-Commiphora-Euphorbia cuneata community 19. Salvadora-Hyphaene-Dobera glabra community 20. Acacia-Trichellia emetica-Delonix community 21. Acacia asak-Commiphora community 22. Breonadia-Nuxia oppositifolia community 23. Olea europaea community 24. Acacia etbaica community Fig. 7. A view of Malaki Dam Fig. 8. Terraced landscape of Fayfa Mountains. 17 Fig. 9. Agricultural Terraces in Jabal Haps. Fig. 10. A view from Jabal Hashar. 18 A 2. Foot-hills and Escarpments. The mountains of Jizan Region occupy the eastern side of the study area. It reaches a height of about 2000 m. The west facing slopes are steep while its eastern side slopes gently towards the inland plateau. The mountains are generally distinguished by crystalline basement rocks with pre-Permian granites, diorites, green stones, marble and quartzite. Gravels, sand, silt and clay are also found at the base of the mountains. The foothills are characterized by rocky slopes, cliffs and crevices with granite, sandy soil whereas the hilly areas are generally formed of rocky cliffs, rocky ridges, granite boulders, granite outcrops, granite sandstones and crevices. The highest peaks of the mountains are heavily populated with new houses and agriculture lands added every year. The Fayfa Mountains commonly known in Arabic as 'Jabal Fayfa', is one of the mega relief centres of the southwestern region of Saudi Arabia, as far as the vegetation is concerned. Characterised by a mosaic environment, these hill-tracts hold a relatively rich and diverse flora. Elevations of these undulating mountains vary from 900 m (Al-Ghardha) to about 2000 m (Al-Abseeya); and extend over several kilometers along a roughly north-south axis. On the southern side, these mountains join the mountains of Yemen and on the north with the mountains of Bani Malik. Compared to the eastern side, the west facing slopes of the mountains are steep and are characterized by dense vegetation. The eastern slopes are the rain shadow regions and are less species rich. Although the mountains receive immense amount of water from monsoon rains, most of the vegetation units are appear to be of secondary in origin. Dominant members of the plant community between 1500-2000 m include: Acacia mellifera, A. seyal, Juniperus procera, Carissa edulis, Euclea schimperi, Ficus sycomorus, Catha edulis, Dracaena ombet, etc. Most of the terrain in the Fayfa Mountains, which have been converted into agricultural terraces in the past, are now abandoned. The natural vegetation of these slopes is now replaced by the secondary vegetation or by exotic weeds. A considerable number of weed-species, such as Tridax procumbens, Chloris barbata, etc and most recently Opuntia dillenii and O. ficus-indica had found their entry into the Kingdom through these mountains. Among these Opuntia spp. are vastly spreading in the region. The ground cover along the slopes is composed of Rhychelytrum repens, Panicum maximum, Chloris gayana, Brachiaria leersoides, Cenchrus ciliaris, etc. Woody herbs and dwarf shrubs are also present along these steep slopes. Fayfa Mountains is not a single steep escarpment but a series of mountain ranges which are cut by deep valleys. The elevation of the Fayfa Mountains from the foot-hills is gradual till it reaches at an altitude of about 1300 m. Further elevation of the mountain towards the summit is somewhat steep. The hillocks on the outerside of the mountain range are less than 700 m high. The vegetation on these hillocks is somewhat sparse and in a highly degraded state due to heavy grazing and flash-floods. The vegetation of the low lying areas is dominated by Acacia etbaica along with occasional trees of A. mellifera and A. asak. Commiphora spp. and Acacia ehrenbergiana are the main componets of the hills below 500-900 m. Other trees such as A. abyssinica, Combretum molle, Tichellia emetica, Tamarindus indica, Ziziphus spina-christi, Dobera glabra, Mimusops laurifolia and Delonix elata are also dominant but in small restricted localities of the west facing slopes. Further east,19 the region has another set of mountains with altitudes ranging from 800-1200 m. Top soil in this part is also highly altered as it eroded away in heavy rains. Fig. 11. Vegetation in Jabal Tallan Fig. 12. Mimusops laurifolia (Frossk.) Friis 20