Phenotypic plasticity is frequently highlighted as a key factor in plant invasiveness, as it enables invasive species to adapt to diverse, complicated habitats. Trianthema portulacastrum is one of the most common aggressive species that threaten different crops around the world. Phenotypic plasticity in T. portulacastrum was investigated by comparing variation in germination, vegetative macromorphology, photosynthetic pigments, stomatal complexes, and seed micromorphological traits of 35 samples collected from 35 different localities. One-way cluster analysis and principal component analysis (PCA) were used to classify samples into homogeneous groups based on the measured traits. Pairwise statistical comparisons were conducted between the three resulting groups. The phenotypic plasticity index (PI) was calculated and compared among different groups of characters. Results showed that photosynthetic pigments and macromorphological characteristics had the highest PI, followed by seed micromorphology, and then stomatal complex traits, while germination parameters showed the lowest PI. We propose that soil moisture, salinity, and temperature are the most determinative and explanative variables of the variation between the three classified groups. We strongly believe that the phenotypic plasticity of T. portulacastrum will support species abundance and spread even under expected changes in climatic conditions, in contrast to the vulnerable traditional crops.

Jabal Al-Ward is one of the Hijazi mountains situated between Al-Ulā and Al-Wajh, southwest Tabuk Province, Saudi Arabia’s northwesterly border region. It is considered the highest mountain in this area and is enriched in wildlife. For the first time, the present research aimed to investigate the floristic composition, phytogeographical distribution, and plant diversity in Jabal Al-Ward. One hundred ninety-eight species representing 47 plant families have been identified. The Asteraceae, Poaceae, and Fabaceae represented more than a third of the region’s floristic composition. The perennial species (53.5%) were dominant over the annuals (46.46%). This is a prominent feature in Jabal Al-Ward, where the perennial species may be more tolerant of climatic changeability than the annuals. Seven life form categories were found; therophytes (46.46%) showed to be the most common life form. In addition, there were four main phytogeographical groups: Mono-regional, Bi-regional, Pluri-regional, and Worldwide. The Mono-regional and Bi-regional categories had the highest participation, with 38.5% and 37.4%, respectively. Thirty-six species (18.2%) were found to be native to the Saharo-Arabian region. The Saharo-Arabian region was combined with eight more regions, including Saharo-Arabian/Sudano-Zambesian (12.6%), Irano-Turanian/Saharo-Arabian (9.1%), Mediterranean/Saharo-Arabian (5.6%), Irano-Turanian/Mediterranean/Saharo-Arabian (4.5%), Irano-Turanian/Saharo-Arabian/Sudano-Zambesian (2%), Euro-Siberian/Irano-Turanian/Mediterranean/Saharo-Arabian and Saharo-Arabian/Sudanian (1% each), Mediterranean/Saharo-Arabian/Sudano-Zambesian, and Irano-Turanian/Mediterranean/Saharo-Arabian/Saharo-Zambesian (0.5% each). The current study demonstrated the highest species richness compared to earlier research on various locations in Tabuk Province. In future work, the species and endemic richness along elevation gradients should be studied in Jabal Al-Ward. As well as the IUCN status of each taxon, the DNA barcoding of endangered species will be of great significance if applied in the surveyed area.

The genus Silene L. is one of the largest genera in Caryophyllaceae, and is distributed in the Northern Hemisphere and South America. The endemic species Silene leucophylla and the near-endemic S. schimperiana are native to the Sinai Peninsula, Egypt. They have reduced population size and are endangered on national and international scales. These two species have typically been disregarded in most studies of the genus Silene. This research integrates the Scanning Electron Microscope (SEM), species micromorphology, and the phylogenetic analysis of four DNA markers: ITS, matK, rbcL and psb-A/trn-H. Trichomes were observed on the stem of Silene leucophylla, while the S. schimperiana has a glabrous stem. Irregular epicuticle platelets with sinuate margin were found in S. schimperiana. Oblong, bone-shaped, and irregularly arranged epidermal cells were present on the leaf of S. leucophylla, while Silene schimperiana leaf has “tetra-, penta-, hexa-, and polygonal” epidermal cells. Silene leucophylla and S. schimperiana have amphistomatic stomata. The Bayesian phylogenetic analysis of each marker individually or in combination represented the first phylogenetic study to reveal the generic and sectional classification of S. leucophylla and S. schimperiana. Two Silene complexes are proposed based on morphological and phylogenetic data. The Leucophylla complex was allied to section Siphonomorpha and the Schimperiana complex was related to section Sclerocalycinae. However, these two complexes need further investigation and more exhaustive sampling to infer their complex phylogenetic relationships.

Ricinus communis L. (Euphorbiaceae, Acalyphoideae) is a highly variable species known as the castor oil plant. This study aimed to describe R. communis using several methodologies, such as vegetative morphometry, leaf surface ultrastructure, soil analysis, and gas chromatography-mass spectrometry (GC-MS) analysis, to understand the diversity of this species. The morphological analysis revealed that some samples had purple stems while others were grayish-green. The purple-stemmed R. communis phenotype reflects the intra-specific diversity of the species. The multivariate analysis of 25 R. communis samples based on 34 vegetative morphometric characteristics revealed that they belonged to three main groups (morphotypes). Each group attained some specific characteristics discriminating it from the other groups. Selected samples from each group were investigated using SEM, soil analysis, and GC-MS. The performed GC-MS technique revealed that six major compounds were detected in the chromatograms of the studied samples. The highest percentages of n-Hexadecanoic acid and 9,12,15-Octadecatrienoic acid were recorded. Ricinus communis demonstrated adaptive growth capability, where plants inhabiting coastal sites are salt-sensitive, while inland plants are relatively drought-tolerant species. The intra-specific variation between R. communis morphotypes indicated the possibility of the direct and indirect use of these varieties in genetic improvement programs of the species.

Allium (Amaryllidaceae) is diverse and taxonomically problematic, with controversial subdivisions and polymorphic species. In Egypt, the genus has not been investigated satisfactorily in terms of palynology. The present study aims to provide palynological information on the endemic and near-endemic species for the first time in Egypt and to characterize the investigated taxa's pollen diversity. Pollen morphology of twenty-one Allium taxa was studied comprehensively by scanning electron microscopy. Twenty-five traits were surveyed, then subjected to Hierarchical Cluster Analysis (HCA) and Principal Coordinate Analysis (PCoA). Pollen grains are monads, heteropolar, monosulcate, or trisulcate, small to medium-sized (P = 10.44 − 29.76 μm, E = 18.97 − 59.24 μm), and the shape is peroblate or oblate. The sulcus may be anasulcate, meridionosulcate, or subzonasulcate. Sulcus ends are blunt, pointed, rounded, or undulated. The exine ornamentation is variable and diversified between the distal pole and the equator. The current study highlighted the importance of pollen characteristics such as pollen size parameters, pollen shape, aperture type, polar outline, sulcus size parameters, sulcus type and end shape, distance between sulcus ends, exine ornamentation, presence or absence of perforations on the exine, and perforations size and density for the discrimination among Allium taxa in Egypt. The HCA confirms that pollen morphology has limited taxonomic usefulness at the sectional level for the studied taxa. While the PCoA results were more informative to visualize the infrageneric classification based on the studied palynological traits. A dichotomous identification key of twenty-one Allium taxa in Egypt based on palynological data is presented.

Balanites aegyptiaca or Desert Date (Zygophyllaceae) is widely distributed in arid and semi-arid regions in Africa and South Asia. The current study aims to identify the infraspecific variation between B. aegyptiaca native to Egypt and Saudi Arabia. Detailed macro- and micromorphological analyses of leaflets, petioles, stems, spines, and fruits were performed using a light and Scanning Electron Microscope (SEM). Statistical analysis was performed by using the relevant R- software packages. Leaflet shape and apex, leaflet length/width ratio, leaflet indumentum density, and the petiole length were recorded. Based on these traits, the present study suggests the existence of one variety, “B. aegyptiaca var. aegyptiaca” in Makkah, Saudi Arabia. At the same time, two varieties were recorded in Egypt “B. aegyptiaca var. aegyptiaca and B. aegyptiaca var. tomentosa”.