The flora and fauna of Arabia, particularly southern Yemen, has recently attracted the interest of many authors. In this study, the genus Heliotropium L. (Boraginaceae) is taxonomically revised in southern Yemen. Ten species are recognized. Nomenclature, typification, representative specimens and a diagnostic key to all species are provided, along with their distribution in southern Yemen. The taxonomically most valuable characters in the genus are those of flowers (calyx, corolla, androecium and gynoecium) and nutlets, and those characters are thoroughly investigated and discussed. Both light and scanning microscopy are used in the investigation. Papillate anther apices (brush-like) were recognized in some species. Connate anthers and deep or shallow ventral circular depressions on the nutlets were found to be useful in distinguishing members of H. sect. Orthostachys (viz. H. strigosum, H. rariflorum and H. ovalifolium), while winged nutlets were found only in H. pterocarpum. The length and hairiness of the style and stigma also proved to be taxonomically useful.

Introduction Boraginaceae Juss. s.l. is a very wide and diverse family; it was recently placed in the lamiid clade in APG IV (Angiosperm Phylogeny Group, 2016). The delimitation of Boraginaceae Juss. s.l. is problematic since the family concept is too broad. On the basis of floral and nutlets/seeds characters, Gürke (1893) recognized four subfamilies:

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.

The genus Ononis comprises 86 species worldwide distributed in temperate regions. It is represented in Egypt by ten species. During recent excursions to the mountains of southern Sinai Peninsula, a newly recorded species, namely O. viscosa subsp. breviflora, was collected. This new record was previously confused with O. sicula. These two species can be differentiated by corolla length and shape. This study provides a full taxonomic revision of the genus for the flora of Egypt, updated nomenclature for all taxa, amended descriptions, detailed hand drawings, and a diagnostic key to the species. The most valuable diagnositic characters in the taxonomy of the genus in Egypt are discussed. After critical examination and literature study, we found that two names (O. serrata and O. vaginalis) needed to be lectotypified.

The two endemic plant species Silene leucophylla and Silene schimperiana (Caryophyllaceae) are native to the Sinai Peninsula which is considered as one of the floristically richest phytogeographical hot spot regions in of the Mediterranean basin. The biodiversity of the Sinai Peninsula is crucial for conservation and sustainable development in the area. Endemic plant species of the Sinai Peninsula are vulnerable to anthropogenic threats due to their relatively low population sizes. In the current study, we reinvestigated the taxonomic statues of two medicinally important and endangered species. The integrated approach involved macro- and micro-morphological traits using a Scanning Electron Microscope (SEM) as well as phylogenetic analysis were conducted, while phylogenetic analysis were also conducted. Phylogenetic reconstruction using Bayesian Inference based on DNA sequences of nuclear (ITS) and chloroplast (rbcL and matK) markers retrieved the species phylogenies successfully. Silene leucophylla and Silene schimperiana were placed phylogenetically within the whole genus. The sectional classification of the two species was confirmed. Silene leucophylla was placed in section Siphonomorpha while Silene schimperiana allied to section Sclerocalycinae. The current study reaffirmed that the integration of various morphological and molecular approaches is useful for identifying and, determining the taxonomic statues, and revealing the phylogenetic positions of these two endangered plant taxa.