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Available online xxxKeywords: Ecology Halophyte Mesembryanthemum crystallinum Relative growth rate Nile delta Conservation a b s t r a c t Ice plant (Mesembryanthemum crystallinum L.) is an important stress-tolerant halophyte distributed in saline areas along the Mediterranean coast of the Nile delta, Egypt. Plant communities dominated by M. crystallinum were studied in different habitats. The application of TWINSPAN classification based on 77 species recorded in 50 stands, led to the recognition of four vegetative groups, which are categorized under three communities. The first is salt marsh community co-dominated by M. crystallinum and Senecio glaucus L. The second is sand dune community dominated by Hordium murinum L. The third is sand flat community dominated by M. crystallinum. Electrical conductivity (EC), sodium ion concentration, Sodium Absorption Ratio (SAR) and sand fraction are the main controlling factors in the distribution of the different vegetative community. The distribution of M. crystallinum community was influenced by calcium carbonate, pH, E.C. and calcium.Various growth parameters including root, shoot and total fresh weight, diameter, leaf area, number of flowers and fruits were measured at two-week interval in the three habitats (sand dune, sand flat and salt marsh). The sand dune and salt marsh habitats, which are threatened by anthropogenic activities, were optimizing growth, flowering and fruiting of M. crystallinum.

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Malva parviflora (little mallow) is a wild herb with agricultural importance in Egypt, where it is cultivated as a food crop. The main objective of the present work was to study the distribution and common associated species of the arable weed, M. parviflora, in the Nile Delta, Egypt. In addition, the diversity and behavior of the common species along the prevailing environmental conditions were assessed. Fifty stands, representing five common habitats (crop fields, orchards, canals, drains and roadsides), were selected. Eighty-five species and one variety (50 annuals and 36 perennials) were recorded. Therophytes dominated the other life forms and biregional taxa contributed the highest chorological elements. Malva parviflora is a therophytic plant that has a Mediterranean distribution intermingled with Irano-Turanian elements. Moreover, the highest coverage percentage of M. parviflora was recorded in the canal banks. Four vegetation groups that represented the distinct habitats were produced by the application of a two-way indicator species analysis and a detrended correspondence analysis as a classification and ordination technique, respectively. Vegetation group C, which inhabited the crop fields, was the most diverse. A canonical correspondence analysis indicated that calcium carbonate, organic carbon, carbonate, potassium and the potassium adsorption ratio and electrical conductivity are the most effective soil variables on the distribution of M. parviflora and its associated species in the different habitats. It was found that M. parviflora was affected greatly by calcium carbonate, sand and magnesium. In addition, it was significantly associated with soil bicarbonate. Such a study could help in managing this important agricultural weed.