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In a field study conducted around Lake Manzala (Egypt) during 1995–1996, the distribution of the floating-leafed lotus (Nymphaea lotus L.) in irrigation canals and ricefields was analyzed by classification and ordination methods. Environmental factors associated with its abundance and distribution were evaluated. A data set of 30 stands of lotus and nine environmental variables was analyzed by Canonical Correspondence Analysis (CCA) ordination relating environmental factors to the occurrence of the weed. Ordination analysis detected a strong association between soil organic matter and fine sediment (silt + clay) in the distribution of lotus. Water variables were less important. The density of lotus averaged 3.3±0.49 plants m−2 in the irrigation canals and 6.6±1.4 plants m−2 in the ricefields. The phytomass of lotus ranged from 877 g m−2 in the pure stands to 226 g m−2 in ricefield habitats. The highest proportion of lotus phytomass was allocated to leaf blade, with values reaching 40% of total phytomass in the infested ricefields. Allocation proportions to other plant organs varied between natural and ricefield habitats. Lotus plants allocated more dry matter to vegetative reproduction than to sexual reproduction. The ratio of vegetative to sexual reproduction ranged from 3.48 in the pure stands to 9.63 in infested ricefields. Populations of lotus showed wider variation in leaf area classes in pure stands than in rice stands. Presence of lotus as a weed in ricefields significantly reduced the growth and grain yield of the crop, indicating the risk of its spreading as an invasive weed.

Age-induced changes in 1) nocturnal and diurnal acidity fluctuations that coincide with the ongoing environmental conditions, 2) the build up of abscisic acid (ABA) in plant roots and leaves during sunrise, midday, and sunset in all growing stages, 3) the changes in phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activities as key enzymes of the photosynthetic pathways of C3 and CAM, 4) leaf water potential (ψ1), and 5) Km and Vmax for PEPC to express its activity and affinity, were studied in Mesembryanthemum nodiflorum during transition from C3 to CAM mode of CO2 fixation. The acidity during sunset in mature stage was higher than in earlier stages and reflected the impact of environmental conditions on physiological and metabolic changes. Moreover, the higher acidity during sunrise and sunset was observed during the senescence than the mature stage; this might be due to CO2 release and oxygen intake during senescence induced ethylene formation that lead to increased malic acid formation. The ABA concentration was high in M. nodiflorum leaves, but stomatal closure was insensitive to elevated ABA concentrations recorded. Vmax of PEPC, Km, and the affinity of PEPC during later stages indicated the ability of PEPC to fix CO2 taking up at night in CAM cycle of M. nodiflorum. Less affinity during sunrise indicated inhibitory effect of malate on PEPC during the release of CO2. The second peak of PEPC activity before sunset caused CO2 fixation. The RuBPCO was inactive at night. Slight increase in ABA during sunset, and night drop in air temperature and increase in relative humidity reduced markedly transpiration rate without decreasing ψ1.

Coastal ecosystems in the Arabian Gulf region are under increasing pressures from hostilities and other developmental activities; the region has a long history of crude-oil pollution. Because of the high ambient temperature, oil deposited along the coastline or inland evaporates, leaving a semi-solid tar. In Qatar, to clean up the polluted sites, the deposited tar is stripped off and dumped in the coastal marshes as confluent dome-shaped piles. Flowering plant colonization of tar-piles is described here as a chrono-sequence, ranging in age from 2 to 14 years. The successional patterns in vegetation, seed bank, species diversity and plant growth were predicted from tar-pile disturbances with different ages and tar content. The success of natural plant colonization and the establishment of plant communities on the tar-pile disturbances depend upon: (1) age of the tar-pile disturbances, (2) tar content of the piles and soil physico-chemical properties, (3) soil moisture content, (4) structure of plant communities in the surrounding landscape, (5) size of the disposal sites and the method of dumping, and (6) prevailing environmental conditions. A management and restoration framework is proposed to optimize the natural recolonization of tar-piles. To retain these ecosystems in a self-sustaining state, some native plant species might be used including: Aeloropus lagopoides, Aizoon canariense, Anabasis setifera, Fagonia indica, Mesembryanthemum nodiflorum, Reichardia tingitana, Salsola imbricata, Suaeda aegyptiaca, Senecio glaucus, Sporobolus arabicus, Zygophyllum quatarense, and Zygophyllum simplex. To clarify the biological and chemical aspects of the problem, further research on the chemistry of tar-polluted soil and its vegetation in relation to the food web is needed.

Current knowledge on the basic radionuclide tolerance indicates that plants may develop mechanisms preventing the damaging effects of radionuclide stress. The radionuclides content was determined in the Mediterranean coastal black sand soil and in the edible portions of the four food crop plant species, viz., Eruca sativa, Lycopersicon esculentum, Pasidium guajava and Mangifera indica. Biochemical and nutritional constituents were assessed to elucidate the possible effect of radionuclides on the edible portions of the plants. The ability of the four study plant species to accumulate Uranium and Thorium in their edible portions from the coastal black sand soil is higher than that absorbed from the inland agricultural soils. The nutritional constituents were affected by the high concentrations of Uranium and Thorium in the plant tissues.

SummaryThere is very little information on effects of particulate pollution from cement factories in the Middle East and northeastern Africa. Variations of natural vegetation, germinable soil seed bank and species diversity were therefore investigated amongst four study sites situated at different distances from the Suez Cement Company factory, south of Suez, Egypt. The composition of plant life-forms was similar in both vegetation and seed-bank communities, with only site-dependent differences in their proportional values. For the standing vegetation, chamaephytes attained the highest relative density and cover, while hemicryptophytes and geophytes exhibited the lowest values. Germinable soil seed bank of all life-forms tended to increase with distance from the cement-dust pollution source. Vegetation, seed rain and seed banks of hemicryptophytes and geophytes were the most affected by cement-kiln dust accumulation in the area. The ratios of seed-bank/seed-rain in all life-forms were less than unity, with a narrow range of variation amongst sites and species. The germinable seed bank was more affected by cement-kiln dust accumulation than the seed rain in all species and life-forms. The species diversity of perennial plants was greater than that of annuals, with values increasing as distance increased from the cement-dust pollution source. Diversity in the standing vegetation Was higher than that of the germinable seed bank. Differences in the standing vegetation and seed-bank reserves were observed in the different study sites. According to their response to cement-dust accumulation, the plant species (listed in text) in the study area were separated into four major groups: (1) tolerant species; (2) non-tolerant species; (3) species having intermediate tolerance; and (4) indifferent species. Management considerations for the conservation of vegetation in cement quarrying sites and around cement factories were put forward to optimize recovery and restoration of vegetation in sites polluted by cement dust.

The present study provides quantitative estimates of the vegetation structure and distribution of the plant communities in Tihamah coastal plains of Jazan region in relation to the soil properties. The factors affecting the species distribution and correlation between the vegetational gradients and the edaphic variables are discussed. Eight major community types constitute the major part of the natural vegetation of the study area and are dominated by nine perennials: Ziziphus spina-christi, Calotropis procera, Leptadenia pyrotechnica, Suaeda monoica, Panicum turgidum, Salvadora persica, Acacia tortilis, Tamarix mannifera and Cyperus conglomeratus . The results of this study confirm that the study area is a tropical desert and belongs floristically to the Sudan territory and also that therophytes are the most frequent life-form in the communities. Analysis of the correlation between the vegetational gradients and the edaphic factors show that soil pH, moisture, electric conductivity, organic carbon, calcium carbonate, bicarbonate, soil cations: sodium, potassium, calcium, and the sodium adsorption ratio are the main operating edaphic factors in the area.

The effect of Cleome droserifolia shoot extract on its seed germination and seedling growth was examined. The possible allelopathic effects on the soil mycoflora were also assessed. The plant water extract caused negative effects on the seed germination and seedling growth, i.e. Cleome droserifolia is autotoxic. The soil mycoflora exhibited suppressed mycelial relative growth rate, spore germination, sporulation and reduced length of the germ tube in response to increased extract concentrations. Due to the allelopathic effects, the number of fungal species and the total count in the rhizosphere was less than that in the non-rhizosphere soil. The species with relatively high colony counts in both rhizosphere and non-rhizosphere soils, such as Aspergillus niger, were less inhibited by the plant water extract. The two species Penicillium chrysogenum and Penicillium funiculosum were the test fungi most sensitive to the allelopathic effects of Cleome droserifolia. Rhizopus stolonifer was the only isolated species found to be resistant to the allelopathic effects.

The floristic composition and species diversity of Brassica nigra communities were investigated in Beni Suef Governorate, Egypt. In 46 stands, a total of 49 species belonging to 42 genera and 18 families were recorded. Vegetation classification and ordination distinguished seven groups: two in reclaimed land only, three groups in old cultivated land only, and two that occurred in both types of land. The species that dominated these groups were Brassica nigra, Sonchus oleraceus, Beta vulgaris, Cichorium endivia, Euphorbia helioscopia and Anagallis arvensis . The highest species diversity was mainly in groups from reclaimed land, and in wheat compared to other crops. Edaphic factors, especially soil texture, CaCO 3 and organic carbon, contributed significantly to explaining the distribution of some weed species, but not with that of B. nigra. The allelopathic potential of Brassica nigra reported in previous studies did not seem to play a role in community composition. Keywords: allelopathy, Brassica nigra , vegetation, TWINSPAN, weed diversity

An efficient method was developed for high frequency shoot regeneration and plant establishment from nodal segment explants of Rauvolfia serpentina. Among the three different cytokinins (6-benzyladenine (BA), kinetin (Kin) and 2-isopentenyl adenine (2-iP)) tested as supplements to Murashige and Skoog (MS) medium, BA at 5.0 μM concentration was found effective in inducing multiple shoots. Effects of different medium (Murashige and Skoog (MS), Gamborg medium (B5), Schenk and Hildebrandt (SH) and Woody Plant Medium (WPM)) on in vitro regeneration were also evaluated. The highest frequency of shoot regeneration (90%) and maximum number of shoot (45.4 ± 3.2 per explants) with an average shoot length of 4.7 ± 0.21 cm were standardized on WPM supplemented with 5.0 μM BA along with 1.0 μM α-naphthalene acetic acid (NAA). In vitro regenerated micro-shoots rooted best on WPM supplemented with 1.0 μM NAA. Plantlets with well-developed shoot and roots, following acclimation in the greenhouse, were successfully established in field condition, and 90% of plants were survived. The regenerated plants were morphologically normal and did not show any immediate detectable phenotypic variation. The method developed can be successfully employed for large-scale multiplication and long-term in vitro conservation of R. serpentina. Key words: Nodal explants, plant growth regulators, in vitro, plant regeneration, micro-propagation.

An efficient method was developed for plant regeneration and establishment from alginate encapsulated synthetic seeds of Rauvolfia serpentina. Synthetic seeds were produced using in vitro proliferated microshoots upon complexation of 3% sodium alginate prepared in Llyod and McCown woody plant medium (WPM) and 100 mM calcium chloride. Re-growth ability of encapsulated nodal segments was evaluated after storage at 4 °C for 0, 1, 2, 4, 6 and 8 weeks and compared with non-encapsulated buds. Effects of different media viz; Murashige and Skoog medium; Lloyd and McCown woody Plant medium, Gamborg’s B5 medium and Schenk and Hildebrandt medium was also investigated for conversion into plantlets. The maximum frequency of conversion into plantlets from encapsulated nodal segments stored at 4 °C for 4 weeks was achieved on woody plant medium supplement with 5.0 μM BA and 1.0 μM NAA. Rooting in plantlets was achieved in half-strength Murashige and Skoog liquid medium containing 0.5 μM indole-3-acetic acid (IAA) on filter paper bridges. Plantlets obtained from stored synseeds were hardened, established successfully ex vitro and were morphologically similar to each other as well as their mother plant. The genetic fidelity of Rauvolfia clones raised from synthetic seeds following four weeks of storage at 4 °C were assessed by using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. All the RAPD and ISSR profiles from generated plantlets were monomorphic and comparable to the mother plant, which confirms the genetic stability among the clones. This synseed protocol could be useful for establishing a particular system for conservation, short-term storage and production of genetically identical and stable plants before it is released for commercial purposes.

An efficient protocol is described for the rapid in vitro clonal propagation of an endangered medicinal plant, Rauvolfia tetraphylla L., through high frequency shoot induction from nodal explants collected from young shoots of a field grown plant. Effects of growth regulators [6-benzyladenine (BA), kinetin (Kin) 2iP, or α-naphthalene acetic acid (NAA)], carbohydrates, different medium [Murashige and Skoog (MS), Woody Plant Medium (WPM), Gamborg medium (B5), Linsmier and Skoog medium (LS)], and various pH levels on in vitro morphogenesis were investigated. The highest frequency of shoot regeneration (90 %) and maximum number of shoot (35.4 ± 2.3) per explant were observed on WPM medium supplemented with 7.5 μM BA, 2.5 μM NAA, and 30 g/l sucrose at pH 5.8. Well-developed shoots, 4–5 cm in length, were successfully rooted ex vitro at 90 % by a 30-min pulse treatment with 150 μM IBA prior to their transfer in planting substrates. The survival rate of transplantation reached 90 % when transferred to field condition. Genetic stability of micropropagated plantlets was assessed and compared with mother plant using Random Amplified Polymorphic DNA and Inter Simple Sequence Repeats markers. No variation was observed in DNA fingerprinting patterns among the micropropagated plants, which were similar to that of the donor plant illustrating their genetic uniformity and clonal fidelity. This confirms that clonal propagation of this plant using axillary shoot buds can be used for commercial exploitation of the selected genotype where a high degree of fidelity is an essential prerequisite. The work contributed to a better in vitro regeneration and clonal mass multiplication of R. tetraphylla and to develop a strategy for the germplasm conservation of this endangered medicinal plant.

The implications for growth-specific resource allocation and the C 3 to Crassulacean Acid Metabolism (CAM) shift in Mesembryanthemum nodiflorum were studied in the field. The C 3 to CAM shift occurs during flowering and fruiting stages allowing for a delayed shift of phytomass from leaf to sexual organs. This behaviour enables the plants to accumulate the additional resources necessary for maximizing the reproductive output. This attribute in the life cycle of Mesembryanthemum nodiflorum allows its dominance over other annual plants growing at the study site in the deltaic Mediterranean coast of Egypt.

Reproductive behaviour and trade-off between sexual and vegetative reproduction in Heliotropium curassavicum were investigated by monitoring the seedling regeneration and aerial shoot emergence. Life table and fecundity schedule were analysed based on sexual and vegetative reproduction in a naturally growing population in the deltaic Mediterranean coast of Egypt. The seedling and aerial shoot emergence were controlled by variation of site openness, soil moisture content and depth of buried seeds and adventitious root buds in soil. In open sites ( 90% plant cover), recruitment from vegetative reproduction was frequent. The phalanx growth form dominated in closed sites, while guerrilla growth form was superior in the open sites. The overall seedling regeneration decreased with depth of the buried seeds, while the aerial shoots emergence showed an optimal response to variation of depth. The pattern of survival ( l x ), mortality ( q x ) and killing power ( k x ) were similar in both sexual and vegetative reproduction. The sequence of age-specific stages in vegetative reproduction occurred over shorter time than in sexual reproduction. The expectation of future life ( e x ) was stage specific and decreased with age. In both sexual and vegetative reproduction, the reproductive rate ( l x b x ) increased and the reproductive value ( V x ) decreased with age. The net reproductive rate ( R o ) and intrinsic rate of increase ( r ) were higher in sexual reproduction than in vegetative reproduction. In accordance with r- and k -selection, the species has a high degree of r -selection in vegetatively open sites, and acquires k -selection strategy in vegetatively closed sites.

Ebcnus armitagei Schweiuf. et Taub(Leguminosae) is a perennial woody species endemic to the western Mediterranean coast of Egypt and Libya The species is uery rare and restricted to a narrow range of distribution. Growth, phenology, seed output, and predation by the bruchid beetle Callosobruchus maculatus F. (Bruchidae—Coleoptera) of a naturally growing population were monitored. Growth and phenology are highly seasonal and correlated with precipitation and temperature. Up to 48.4% of the population is in the juvenile stages, which experience high mortality. Seed predation is extraordinarily heauy. An auerage of 94.4% of seeds in different stages of maturity are consumed or damaged by C. maculatus. Habitat change and biotic factors within populations including seed predation are threatening the species’existence in the wild. The following are some possible measures for conservation of E. armitagci: (1) small scale habitat conservation (sanctuary), (2) establishment of new populations by artificial means, (3) establishment of a gene (seed) bank, (4) encouraging botanical gardens to conserue the species, and (5) field application of selective insecticides to control the seed predators but not to destroy beneficial insects. Resumen: Ebenus armitagei Schweiuf: et Taub (Leguminosae) es una especie de arbol perenne, maderable y endemica de la costa oeste del Mediterraneo, en Egipto. Esta especie es muy rara y restringida a un limitado rango de distribucion. El crecimiento, la fenomenologia, la produccion de semillas y la predacio por el coleriptero Callosobruchus maculatus F. (Bruchidae-Coleoptera) de una poblacion silvestre fueron monitoreados. El crecimiento y la fenomenologia son altamente estacionales y correlacionados con la precipitacion y la temperature. La poblacion tiene basta 48.8% de sus indiuiduos en el estado juvenil, el cual tiene un alto grado de mortalidad, La predacion de semillas es extraordinariamente intensa. Un promedio de 94.4% de las semillas en diferentes estados de madurez son consumidas o danadas por C. maculatus. El cambio de habitat y los factores bioticos dentro de las poblaciones, incluyendo la predacion de semillas, estan amenazando la existencia de la especie en suestado silvestre. A continuacion se dun algunas posibles medidas para la conservacion de E. armitagei: (1) conservacion a pequena escala del habitat, (2) establecimiento de nuevas poblaciones por medios artificiales, (3) establecimiento de un bunco de genes (semillas). (4) impulsar a los jardines botanicos hacia la conservacion de la especie y (5) aplicacion en el campo de insecticidas selectivos para controlar los predadores de semillas pero no para destruir los insectos beneficiarios.

The population ecology of a perennial desert plant [ Cleome droserifolia (Forssk). Del.] was studied in Egypt. Seed bank, seed rain, seed dispersal, seedling and juvenile establishment, and adult population were examined. Complete survivorship curve, life table and fecundity schedule were constructed for a naturally growing population. The results were discussed in the context of species conservation. The following recommendations are essential to conserve the species and to assist in devising a management strategy: (1) at least one population should be maintained in situ for conservation, scientific interest, education and aesthetics; (2) harvesting in the remaining populations should be restricted to the oldest individuals; (3) plant collectors, botanical gardens and herbaria should collect seeds; and (4) experimental research is needed on in situ and ex situ propagation of the species.

The two investigated species Anastatica hierochuntica L. Cruciferae and Asteriscus pygmaeus (DC.) Coss. et Dur. Compositae were raised under different watering regimes. Growth, phenology, resource allocation and competition for water were monitored. The following results were obtained: (1) The relative growth and net assimilation rates were dependent on both age and watering regime. (2) During seedling and juvenile stages, plants had more roots than shoots. Towards the end of the life cycle, there was a redistribution of resources from vegetative to reproductive structures. (3) Plants were able to adjust the timing of phenological events and water use in accordance with the watering regime. (4) Under high water treatments, A. hierochuntica was competitively inhibited, while under low water treatments A. pygmaeus was competitively inferior. (5) Due to these species’ habitat accessibility there is a need to protect and safeguard their existence.

Summary Phenology, pigment content, succulence ratio and the diurnal changes of water and proline contents were investigated in green and yellow leaf parts of Zygophyllum album , Z. decumbens and Z. coccineum . Phenological patterns and the leaf area index were followed monthly during 1988. Pigment content, succulence ratio and the diurnal change of water and proline contents were investigated under natural environments in August. The leaf area index curves of the three species showed the highest values towards the end of the rainy season. The yellow leaflets and petioles of Z. album showed higher fresh and dry weights than the corresponding green ones. On the contrary, the green leaflets and petioles of Z. decumbens and Z. coccineum showed higher fresh and dry weights than the yellow ones. With the exception of shrivelled leaflets of Z. album , the leaf parts of the species investigated showed high succulence ratio. Phenology and the pigment content results support the concept that the three species undergo leaf senescence followed by shedding in the dry season. The importance of chlorophyll-dependent proline biosynthesis was clarified. The petioles of Z. decumbens and Z. coccineum showed higher proline content than the leaflets. Most leaf parts of the investigated species showed diurnal change of water and proline contents. Irrespective of the species, the relationship was negatively correlated in the green leaflets, the green and yellow petioles. This implies that the three species, although from two different habitats, showed a confirmed generality of proline accumulation, but in different magnitudes by the green and yellow (senescing) leaf parts as a response to water deficit.

Background and Aims Unlike the dispersal mechanisms of many desert plants, the whole dead skeleton of Anastatica hierochuntica is involved in seed dispersal and preservation. This process depends on the hygrochastic nature of the lignified conducting tissue that bends when dry and straightens under wet conditions. An anatomical interpretation of this mechanical movement was investigated. Methods An anatomical study of the stem was conducted on the juvenile plants raised under different water treatments and on the branch-orders of adult A. hierochuntica size-classes. Key Results In the juvenile stem of A. hierochuntica, the area of cortex, conducting tissue and pith increased with water availability. However, the hydraulic conductance decreased, resulting in a better withdrawal of water in waterstressed plants. The anatomical investigation of the hygrochastic mechanism revealed an asymmetric distribution of the cortical tissues, with the conducting tissues of the stem of juvenile and adult plants being larger in the lower side. The hydraulic conductance was better in the basal and middle branch-orders than the terminal ones, permitting better conductance of water to the subsequent branch-orders. Conclusions The lignified conducting tissue of the whole stem, having a hygrochastic nature, controls the movement of the branches. The greater amount of conducting tissue associated with a higher density of wide xylem vessels was observed in the lower side of the stem as compared with the upper side. Consequently, the conducting tissue in the lower side of the stem was suggested to be more effective in the opening process of the curled dry branches through better and more rapid conductance of water. Alternatively, due to the few narrow xylem vessels in the upper side of the stem, it was likely that the conducting tissue in the upper side is more effective in the closing process by providing more rapid drying. The mechanical rise of water and the related hygrochastic efficiency were maximized in the basal and middle branch-orders that are mostly involved in the mechanical movement.

The Red Sea is 1932 km long, and average of 280 km in width. At its widest, in the south near Massawa, it is reaches 354 km wide and this narrows to 29 km at Strait of Bab al Mandab and to about 180 km before it branches to the Gulf of Suez and the Gulf of Aqaba. The latitudinal range of the Sea lies between 30°N and 12° 30’N, it has a long history in association with man’s activities, but the degree of human impact and exploitation has until recently been negligible.

Aromatic gum from Boswellia carteri (olibanum oleogum) has long been used in Egyptian traditional medicine. Cyclooxygenase-1 (COX-1) enzyme inhibitory assay guided purification of the extracts of this resin resulted in five bioactive compounds, 3α- O-acetyl-8,24-dien-tirucallic acid (1), verticilla-4(20),7,11-triene (2), cembrene A (3), incensole acetate (4), and incensole (5). The pure isolates were investigated for their inhibitory effects on COX-1 and −2 enzymes and human tumor cell lines Hep-G2, MCF-7 and RAW 264.7. Compounds 1–5 inhibited COX-2 enzyme by 39.0, 32.7, 60.0, 46.3, and 49.8%, respectively. Furthermore, compound 2 showed an inhibitory concentration of 50% (IC50) at 9 μg/mL against Hep-G2 tumor cell line. This is the first report of COX-1 and -2 enzyme and tumor cell proliferation inhibitory effects of compounds 1 and 2.

Most of the shores in Qatar and other oil producing countries have had a long history of crude oil pollution from different sources. This pilot study was to assess the problem and suggest a management programme for disposing of the collected tar or lessening the impact of tar accumulation. The vegetation on the sites used for dumping tar was used in a field survey to identify bioindicators of tar pollution and of the natural recovery of polluted sites. The phytomonitoring results indicate that recovery of polluted sites can be quite rapid after clean-up and restoration. To facilitate natural plant invasion and colonization, and the restoration of tar piles, the dumping sites must have plant communities with high species diversity and a high percentage of annual plants. Depending on the sand-tar ratio in the piles, artificial seeding of selected plant species (listed) can be applied by using species mixes or single species seeding. Management techniques are suggested to optimize the natural recovery and revegetation of tar-affected coastal marshes.

Limonium delitatulum [Gir.] Ktze.x (Plumbaginaceae) is a salt-tolerant cushion plant with crown attached to the soil surface. Survival, mortality and reproduction, and conservation of the naturally growing population in the Mediterranean region of Egypt were investigated. The following results were obtained. (1) Average mature seed output was 75 632 seeds for the population investigated. About 29.5% of the seeds have the potential to germinate in soil, and out of these germinable seeds, about 7.9% gave seedlings. Juvenile plants were formed by about 5.9% of the seedlings, while about 65% of juveniles reached the mature reproductive stage. (2) The survival curve, life table and fecundity schedule exhibited the high mortality of seeds and seedlings. Juvenile and adults of age 7 years showed a high expectation of future life. The net reproductive rate was 0.36, indicating failure of the population to attain ‘positive’ growth and reproduction. The estimated intrinsic rate of increase was -0.071 per capita per annum. The average generation time of the species was 14.4 years. (3) Vegetative activity occurred throughout the year with maximum leaf area index and leaf appearance rate during April and May. There was a significant negative linear regression between leaf area index and age of plants. (4) The percentage of dead whole individual plants or partially dead individuals in the population increased with age. The number of dead individuals or dead rosettes per individual in the oldest adult cohort exceeded the live individuals or rosettes, respectively. Juvenile and adult plants exhibited a decreased proportion of dry matter to roots. The live/dead phytomass ratios were greater than unity in roots and stems. The leaves showed live/dead ratios of less than unity, being 0.69 in juveniles and 0.34 in adults. (5) The following recommendations are essential to conserve the species and its habitats: (i) creation of small-scale natural salt-marsh reserves within the developed agroecosystems; (ii) professional botanical/ecological management of the natural reserves; (iii) ethnobotanical knowledge of the species; and (iv) ecological research on in situ and ex situ survival and propagation strategies of the species.

Zygophyllum aegyptium A. Hosny sp. nov. (Fam. Zygophyllaceae) is a closely related taxon to Z. album, but can be differentiated by the flowering branches and during fruiting stage. It is distributed in the Mediterranean region of Egypt, Tunis and Cyprus. As a taxon of the genus Zygophyllum in Egypt, Z. aegyptium is ecologically interesting. The species has broad ecological amplitude where it can grow in different habitat types. Z. aegyptium plays an important role in the zonation pattern of the vegetation in the Deltaic coast of Egypt. The zonation usually beings at the coast with a zone of Z. aegyptium community type which builds up sand mounds forming a narrow belt of vegetation runs parallel to the coast.

1. Limonium delicatulum is a salt-tolerant cushion plant. Survival, mortality and reproduction were investigated, and their implications for the conservation of naturally growing populations in the Mediterranean region of Egypt were assessed. 2. The total annual seed output by the entire population was computed to be c. 76 000 seeds. About 29.5% of the seeds had the potential to germinate in soil, and out of these germinable seeds, about 7.9% gave seedlings. The juvenile plants comprised about 5.9% of the seedlings, while about 65% of juveniles reached mature reproductive stage.3. The survivorship curve, life table and fecundity schedule reflected high mortality of seeds and seedlings

Field data verified by green house experiment were used to evaluate the response of Anastatica hierochuntica L. to the amount of rainfall. Field study of the populations was carried out in the runnel and depression microhabitats of gravel and sand sites. Four water treatments, equivalent to 100, 200, 500 and 1000 mm rainfall, were used to simulate different levels of water availability. Under 500 and 1000 mm rainfall, the size-class structure of A. hierochuntica populations consists of a high proportion of large size-class individuals, while a higher proportion of small size-class individuals was obtained under 100 and 200 mm rainfall. The dry skeletons of A. hierochuntica can be used as a “rain gauge” to predict the amount of rain or water received. The dominance of small size-classes (from 500 mm rainfall produce large size-classes (>64 cm3). Small size-class individuals produced under low amounts of rainfall allocated up to 60% of their phytomass to the reproductive organs. Allocation to reproductive organs decreased with the increase in the amount of rainfall, while allocation to the stem increased in large size-class individuals produced under the highest amount of rainfall (1000 mm) reaching 54%. Increased allocation to stem in large-sized individuals favours the hygrochastic seed dispersal role in the plant. The root/shoot ratio decreased with the increase of the individual size-class, i.e. under high rainfall treatments. Higher values of relative growth rate, net assimilation rate and leaf area index were obtained under high water treatments. Conversely, less expanded leaves, i.e. lower specific leaf area, were manifested in the lowest water treatments.

Laboratory experiments were undertaken to investigate the autotoxic effects ofAnastatica hierochuntica and possible effects on five other desert plants:Rumex cyprius, Trigonella stellata, Diplotaxis harra, Cleome droserifolia, andFarsetia aegyptia. Seed germination, seedling growth, and cell division of all species tested were inhibited by the shoot aqueous extract ofA. hierochuntica. A gradual increase in the percentage of prophase and decrease in the other mitotic stages as well as the mitotic index were observed with increasing extract concentration. At an extract concentration of 8% the mitotic index was reduced from the control by 55% inC. droserifolia, 54% inT. stellata, 45% inF. aegyptia, 43% inA. hierochuntica, and 35% inR. cyprius. The inhibitory substances are apparently released onto soil by repeated washing of the standing plants by rain and dew interception.