For the first time, an updated checklist of Acacia, Senegalia and Vachellia species in Egypt is provided, focusing on the exotic species. Taking into consideration the retypification of genus Acacia ratified at the Melbourne International Botanical Congress (IBC, 2011), a process of reclassification has taken place worldwide in recent years. The review of Acacia and its segregates in Egypt became necessary in light of the available information cited in classical works during the last century. In Egypt, various taxa formerly placed in Acacia s.l., have been transferred to Acacia s.s., Acaciella, Senegalia, Parasenegalia and Vachellia. The present study is a contribution towards clarifying the nomenclatural status of all recorded species of Acacia and its segregate genera. This study recorded 144 taxa (125 species and 19 infraspecific taxa). Only 14 taxa (four species and 10 infraspecific taxa) are indigenous to Egypt (included now under Senegalia and Vachellia). The other 130 taxa had been introduced to Egypt during the last century. Out of the 130 taxa, 79 taxa have been recorded in literature. The focus of this study is the remaining 51 exotic taxa that have been traced as living species in Egyptian gardens or as herbarium specimens in Egyptian herbaria. The studied exotic taxa are accommodated under Acacia s.s. (24 taxa), Senegalia (14 taxa) and Vachellia (13 taxa). Identification keys for the studied genera, generic groups and species have been provided using different taxonomic criteria. For each taxon, the validated name with the first citation followed by relevant Egyptian citations, typification, synonyms, distinctive features, origin, ecology (when available), utilisation and selected specimens are provided. The study revealed the presence of 22 newly recorded taxa in Egypt. Additionally, a list of excluded, unvalidated and unresolved names is given.

Trichomes are extensions of the epidermis, frequently used as diagnostic traits for determining plant species. Solanum L., 1753 is a widespread and taxonomically complex genus. Although the genus Solanum has been the subject of numerous types of research, little attention has been given to the trichomes of the wild species found in Egypt. Therefore, the objective of the current study was to examine trichome types in ten wild Solanum species and assess their taxonomic importance. Using light, scanning electron microscopy and line drawings, indumentum characteristics on the abaxial leaf surface are investigated. The results showed a wide range of variation in trichome density on a 1 mm2 area of leaf blade (sparse, moderate, and dense), nature (glandular or non-glandular, simple or stellate), and structure (number of composing cells in simple non-glandular and glandular stalk and head; the number of radiating rays in stellate hairs). SEM revealed the existence of unique wax structures, including warty granules in addition to flakes. Our observations are consistent with the general characteristics of the subgenus Leptostemonum and the subgenus Solanum. This work provides strong evidence for the separation and interspecific delimitation of the investigated Solanum species using trichome morphology as a significant taxonomic trait.

No reliable evidence summarizes the current state of the floristic and taxonomic knowledge of the Egyptian flora since Boulos (2009). In this study, we critically revised and updated the checklist of native vascular plants of Egypt. The checklist comprises 2,499 native and naturalized vascular plant taxa (1,676 species and 552 infraspecific taxa) from 119 families and 796 genera including 20 ferns, 6 gymnosperms, and 2,473 angiosperms. In the angiosperms, Asteraceae, Poaceae, Fabaceae, Amaranthaceae, Caryophyllaceae and Brassicaceae show the greatest species richness (> 100 taxa). The Sinai Peninsula contains the richest flora with 1,473 taxa. Based on our critical revisions, names of 32 families, 41 genera, and 409 species have been changed in comparison to the latest checklist. In addition, 52 plant species are excluded from Flora of Egypt in this work, while one new family (Cannabaceae), 23 new genera, 189 new species, 61 new subspecies, and 41 new varieties are added. Concerning the species endemism; authors adopted 74 endemic taxa restricted only to Egypt, and 207 near- endemic taxa that co- occur in adjacent countries. This updating checklist will serve as an essential background and reference for scientists and students interested in the Egyptian flora, and also for conservation projects in Egypt.

Capsella bursa-pastoris (Brassicaceae) is one of the most successful tetraploid species in the world. It showed high morphological diversity within Egyptian populations. The morphological investigations of herbarium specimens and fresh collected populations grouped them under three distinguished morphotypes (Lobed "L"; Simple "S" and Lobed-Simple "LS") depending mainly on the basal leaves structure. This high degree of phenotypic variation has received our critical attention. Until recently, the previous studies on C. bursa-pastoris attributed its phenotypic variation to environmental factors. But in Egypt, these three morphotypes were traced in mixed populations along with the species geographical range, so the environmental factors have no influence on their distribution or phenotypic variation. Accordingly, our primary concern in this study was to determine the factors controlling this variation. The cytogenetic studies revealed that the three identified morphotypes are three distinct genotypes with three different chromosome numbers: 2n=2x=16 (diploid) for "L"; 2n=3x=24 (triploid) for "S"; 2n=4x=32 (tetraploid) for "LS". The triploid genotype "S" showed rare occurrence among the studied populations and is postulated to be a hybrid newly recorded in Egypt. Karyotyping of the three genotypes showed significant differences in the genome and chromosomes relative lengths. Molecular study using cpSSR technique supported the cytogenetic results and differentiated the three studied genotypes. The retrieved results revealed that the phenotypic diversity within the Egyptian C. bursa-pastoris populations is genetically controlled.