Taxonomic implications of normal and abnormal stomatal complexes in Indigofera L. (Indigofereae, Faboideae, Fabaceae).

This study is the first to report the foliar and stem epidermal micro-morphology of 13 taxa of Indigofera L. (Fabaceae) using light (LM) and scanning electron microscopy (SEM). The micro-morphological characteristics studied here are related to the epidermal cell shape, size, frequency, anticlinal wall pattern, and stomatal complex types, size, position, frequency, and index. The study revealed 19 major normal stomatal types with eight subtypes and seven major abnormal stomatal types with 13 subtypes. The stomatal index was lower on the abaxial leaf surface than on the adaxial surface. Notably, the adaxial surface of I. hochstetteri had the highest stomatal index (27.46%), while the abaxial surface of I. oblongifolia had the lowest (9.95%). The adaxial surface of I. hochstetteri also displayed the highest average stomatal frequency (38.67), while the adaxial surface of I. spinosa had the lowest average frequency (9.37). SEM analysis revealed that most leaves had slightly sunken to sunken stomata, while stem stomata were positioned at the same level as epidermal cells in most taxa. Indigofera's foliar and stem epidermal anatomy recommends their application as baseline data coupled with other taxonomic data for the delimitation and differentiation of closely related taxa in the genus. The study provides a comprehensive description, illustrations, images, and micrographs of the stomatal types, as well as a taxonomic key for distinguishing the studied taxa of Indigofera.

Investigating the Phenotypic Plasticity of the Invasive Weed Trianthema portulacastrum L.

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.

Taxonomic Revisiting and Phylogenetic Placement of Two Endangered Plant Species: Silene leucophylla Boiss. and Silene schimperiana Boiss. (Caryophyllaceae).

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.