Summary Cytomixis has been observed in pollen mother cells of Vicia faba. Of all eight sites plant materials were collected and investigated, cytomixis has been noted in six. Four of these sites recorded high percentage of cytomixis, where the two other sites show low concentration of this phenomenon. Cytomixis was observed to occur in forms of cytoplasmic connection and direct fusion. The first type is more frequent than second one. Both types of connections were observed in majority of stages of division. The amount of nuclear material transferred from cell to another was variable from small fragments to the entire complement based on the nature of connection. Abnormalities were observed in all sites investigated. Close relationship is clear between the percentage of this parameter and the percentage of cytomixis. The percentage of pollen fertility is clearly affected by cytomixis and abnormalities. Causes of cytomixis in the present study almost refer to environmental stress and pollution.

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The present study was conducted to investigate the potential of the emergent macrophytes Phragmites australis to remediate nutrients and restore an eutrophic wetland (Lake Burullus, Egypt). The plant was sampled monthly for one year from 6 sites distributed equally along the northern and southern parts of this lake. Monthly significant variation in all investigated sediment and water nutrients for the northern and southern sites was recorded. The biomass of P. australis in the southern sites was greater than that of the northern sites; in addition, the above-ground biomass was greater than the below-ground biomass. The above-ground biomass increased from February until it reached its maximum during August and then decreased again. Likewise, the highest nutrient concentrations in the different tissues were recorded at the beginning of the growing season during winter and early spring and then gradually decreased with increasing plant biomass. Moreover, the nutrient content (g/m 2 ) increased from the early growing season (February) and reached its peak during April-August and then decreased. Based on our results, P. australis could be used for the extraction of nutrients to reduce the eutrophication in Lake Burullus, if the above-ground biomass is harvested at its maximum value in August, as was the case regarding the maximum content of most nutrients. ARTICLE HISTORY

The cytological investigation of 12 taxa ofPanicum L. revealed that the vast majority of them have the basic number x = 9 at different ploidy levels. The basic number x = 8 was recorded only in the tetraploid species P. maximum with 2n = 32. The diploid number 2n = 18 was encountered in P. capiilare, P. laevifolium, P. antidotale and P. coloratura (2) with 3B-chromosomes recorded in the latter species. The telraploid chromosome number 2n = 36 was found to exist in P. miliaceum, P. miliare, P. coloratum (1) and P. virgatum. The hexaploid number 2n = 54 was recorded in P. bulbosum, P. dichotomiflorum and P. esculentum. The karyotypes of all accessions were mostly symmetrical and mainly comprised of meta-and submetacentric chromosomes with little variation in length among them within each karyotype. Investigation of chromosome association during metaphase I of meiosis revealed that the frequency of bivalents/cell was the highest among all investigated diploid, tetraploid and hexaploid accessions. Univalents were also frequently encountered in various accessions. These results may indicate that segmental alloploidy has been the major process by which polyploid species have originated.