Brassica tournefortii Gouan. (family Brassicaceae) is one of the five species in the Egyptian flora. Its populations showed notable morpho-plasticity with taxonomic debates, which were not yet resolved. The current study was carried out to assess the species morpho-plasticity and its molecular identity based on ISSR. The study was applied to 27 herbarium and fresh populations, representing all the species distribution ranges in Egypt. The taxonomic revision included 70 morphological characters, revealed five distinct Forms (1-5), radical leaf, and fruit provided the major distinguishable traits among the studied 70 morphological characters based on them the morphologic key is provided to delimit these forms. The pollen grain features using SEM are a pioneer at the infra-specific level, two shapes observed the subprolate (Forms 1& 3) and prolate (Forms 2, 4 & 5). Furthermore, the exine micro-features possess taxonomic value at the infraspecific level. The cluster analysis based on ISSR data revealed two clusters congruent to those developed by morphological and pollen traits. The ISSR results indicated that the species morpho-plasticity is genetically controlled. The study highlights the importance of the multidisciplinary approach to assess the taxonomic identity at the infra-specific level, for the auto-taxonomy of morpho-plastic species. Bangladesh J. Plant Taxon. 27(2): 233-250, 2020 (December)
Pruning Ficus trees in urban green spaces may lead to the accumulation and spread of their leaf litter on the understory vegetation. This study was conducted to evaluate the allelopathic effect of Ficus retusa L. leaf litter on the understory species in urban gardens. A field study showed that the plant cover and species richness of litter-affected plots were lower than those of litter-free areas. The litter-affected soils had substantially lower pH and higher electrical conductivity. In a greenhouse experiment, litter-affected soil significantly inhibited the emergence and growth of understory species selected for the purpose of this study: Melilotus indicus (L.) All., Trifolium resupinatum L. and Amaranthus viridis L. Osmotic potentials equivalent to those of the litter-affected soils did not affect emergence or growth of these species. A spectrophotometric analysis indicated that the litter-affected soils contained larger amounts of phenolics and flavonoids. An HPLC analysis revealed that the litter-affected soils contained higher concentrations of free phenolic and flavonoid allelochemicals. These results demonstrate that F. retusa leaf litter may reduce plant cover and species richness. The significant inhibition in both field and greenhouse experiments could be attributed to phenolic and flavonoid allelochemicals released from the tree litter, as the osmotic potential of the litter had no effect on the understory species. The allelopathic potential of F. retusa leaf litter plays at least a partial role in reducing urban vegetation.
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