Pollen and seed morphology of rhinacanthus nees and hypoestes Sol. ex R. Br. (Acanthaceae) of Yemen

Pollens and seeds of Hypoestes and Rhinacanthus collected from different field localities in Taiz and Soqotra Island, Yemen were investigated by using light and scanning electron microscopes. Pollen grains of Hypoestes were prolate in equatorial view, lobate trigonal to lobate circular in polar view whereas those of Rhinacanthus were subspheroidal and rounded trigonal in polar view. The aperture was tricolporate and exine ornamentation was coarsely reticulate for all species in the two genera. Scanning electron microscopy and morphological observations showed that mature dry seeds of Hypoestes and Rhinacanthus have various sizes and shapes, the surface ornamentations observed were reticulate to cristate, an addition to the tuberculum and papillae. The three Hypoestes species differ in the seed structure which are useful for identification and their high structural diversity provides an important taxonomic value for species differentiation

Anatomy and histochemistry of structures producing aroma in leaves of Sygyzium aromaticum (L.) Merr. and Clausena excavata Burm. f.

Anatomical and histochemical studies on leaves of Syzygium aromaticum and Clausena excavata have been carried out. This study was conducted in order to investigate the relationship between aroma production and a plant's secretory structures. Leaves from the two tropical aromatic plants were sampled from the Institute of Bioscience (IBS) Conservatory Park and transversely sectioned through lamina, midrib and petiole with a sliding microtome for anatomical investigation. Through light microscopy, oil cells and secretory cavities were distributed near the adaxial and abaxial epidermal layers with large in size, up to 60 µm length. Other leaf anatomical characters such as shape of petiole and midrib, pattern of vascular bundle, palisade and spongy mesophyll, the presence or absence of brachysclereids and crystals are also observed. This study also aimed to investigate the leaf's secretory structures responsible for plants' aroma production and to detect the presence of terpenes and essential oil in secretory structures histochemically

Pollen and seed morphology of Justicieae (Ruellioideae, Acanthaceae) of Yemen

Pollen and seeds of 12 genera and 28 species belonging to Justicieae namely, Anisotes, Angkalanthus, Asystasia, Ballochia, Dicliptera, Ecbolium, Hypoestes, Isoglossa, Justicia, Megalochlamys, Rhinacanthus and Trichocalyx were collected from different field localities in Yemen and were investigated using both light and scanning electron microscopes. Nine pollen types were observed whose shapes were prolate, subprolate and spheroidal while the apertures varied from dicolporate, tricolporate, porate to colpate. The exine ornamentation was reticulate in most of the species except Megalochlamyas, which showed perforate ornamentation, and Isoglossa, which showed reticulate to rugulate ornamentation. Scanning electron microscopy and morphological observations showed that mature dry seeds of the genera have various sizes and shapes, the surface ornamentations observed were reticulate, cristate, tuberculate and papillae. In addition, hairs were present in some Ballochia species. The variation in the seed structures between the genera and within the species was useful for their identification and classification; their high structural diversity is of important taxonomic value for species differentiation

Stem and leaf anatomical studies of selected species of barlerieae and ruellieae (acanthaceae) from Yemen

The anatomy of stems and leaves of selected species of tribes Barlerieae and Ruellieae (Acanthaceae) was studied to assess the taxonomic significance of anatomical characteristics in the two tribes. The anatomical characters such as the outline of stems, midribs, petioles, margins, shape of epidermal cells, vascular bundles, stomata, anticlinal cells, cystoliths, aerenchyma cells, layer of wax, layer of hypodermis were observed and analysed. Type of trichomes observed on the leaf surface using Scanning Electron Microscopy and light microscope provides information of taxonomic significance to both tribes and the taxa within them. The trichomes vary from non-glandular (unicellular, bicellular, multicellular, and multiradiate) to capitate glandular. Abundance of long-stalked trichomes was recorded only in Neuracanthus aculeatus. Cystoliths of different size and position are present in epidermis, parenchyma and collenchyma in addition to oil cells in some genera. The placement of Neuracanthus among the recognized tribes of Acanthaceae is assessed using anatomical characters

Pollen and Seed Morphology of Rhinacanthus Nees and Hypoestes Sol. ex R. Br. (Acanthaceae) of Yemen

Pollens and seeds of Hypoestes and Rhinacanthus collected from different field localities in Taiz and Soqotra Island, Yemen were investigated by using light and scanning electron microscopes. Pollen grains of Hypoestes were prolate in equatorial view, lobate trigonal to lobate circular in polar view whereas those of Rhinacanthus were subspheroidal and rounded trigonal in polar view. The aperture was tricolporate and exine ornamentation was coarsely reticulate for all species in the two genera. Scanning electron microscopy and morphological observations showed that mature dry seeds of Hypoestes and Rhinacanthus have various sizes and shapes, the surface ornamentations observed were reticulate to cristate, an addition to the tuberculum and papillae. The three Hypoestes species differ in the seed structure which are useful for identification and their high structural diversity provides an important taxonomic value for species differentiation