Presence Of Silica Bodies Research Articles

Micromorphological variations of trichomes in the genus Ocimum L.

Ocimum L. is an attractive fragrant ornamental plant with medicinal aromatic compounds. The study using digital microscopy revealed the distinct epidermal trichome morphology in five species of Ocimum including O. americanum L., O. basilicum L., O. gratissimum L., O. kilimandscharicum Gurke and O. tenuiflorum L. A distinguished variation in size, shape, type and abundance of trichomes on leaves and stem of all species are described and photographed. Both glandular and non-glandular trichomes scrutinized in all the species in which glandular type comprised capitate and peltate trichomes. On the stem, the longest glandular capitate trichome (GCT) and non-glandular trichome (NGT) were observed in O. tenuiflorum while O. basilicum possessed longest glandular peltate trichome (GPT). In case of foliar trichomes, the longest GCT observed on leaves of O. americanum; and O. basilicum showed the longest GPT and NGT. In the species, the septate or aseptate NGT possessed uni, bi or multicellular base with acute or broad apex. A distinguished variation in the number of cells in stalk and head of GT was observed in the study. Presence of silica bodies in peltate trichome of O. kilimandscharicum was noticed as the characteristic feature. Among the five species, the trichomes were abundant in O. kilimandscharicum; while O. basilicum showed sparse distribution. Trichomes with disrupted cells were also noted in O. americanum. Due to the presence of specific trichome characteristics, the efficient taxonomic key is prepared to identify the taxa at species level.

Characterization of New Cellulosic Cyrtostachys renda and Ptychosperma macarthurii Fibers from Landscaping Plants

ABSTRACT Cyrtostachys renda (CR) and Ptychosperma macarthurii (PM) fibers, as new cellulosic fibers were studied. The objective of this research is to evaluate the fibers from stem, leaf stalk, and frond of these two plants as reinforcement in the polymer composites. The density, chemical composition, functional group, crystallinity index, and thermal stability were studied for CR and PM fibers. From the analysis, the density and thermal stability of both leaf stalk fibers are found almost similar. The highest crystallinity index (55.67%) of the leaf stalk of CR was attributed to the highest cellulosic content (38.99%) and the functional group (C-H stretching). From the results, the optimized properties were found for the leaf stalk of CR fiber. The tensile strength, interfacial shear strength (IFSS), morphology of the leaf stalk of CR were explored. The ultimate tensile strength, Young modulus, and IFSS of the leaf stalk of CR is 51.82 ± 9.41 MPa, 0.69 ± 0.18 GPa, and 3.27 ± 0.5 MPa, respectively. The Scanning Electron Microscopy observation revealed that the leaf stalk fiber of CR possesses anti-microbial properties which has been corroborated through the presence of silica bodies over the fiber surface. Hence, the leaf stalk of CR acts as a potential reinforcement in the polymeric composites for lightweight applications.

Microscopic Chemical Characterization and Reactivity in Cementing Systems of Elephant Grass Leaf Ashes.

Many agrowastes are being used for energy production by combustion in power plants. This process generates huge amounts of ash, which has a potential pozzolanic activity for blending with Portland cement or hydrated lime. In this paper, the ash obtained from elephant grass (Pennisetum purpureum Schum var. purple) leaves (EGLs) was studied, including the silicon content and its distribution, the presence of other compounds, and in addition, the presence of silica bodies (phytoliths). Combustion temperatures of 450 and 650°C produced an unaltered inorganic skeleton (spodogram), whereas at 850°C, there is a sintering process because of high potassium content in the ash. Phytoliths and different types of hairs were identified, and they contained high percentages of silica. Magnesium (mainly as periclase) was distributed in the most porous parts in the interior of the leaves. The silica can react with calcium hydroxide (pozzolanic reaction) forming calcium silicate hydrates (observed by field-emission scanning electron microscopy and thermogravimetric analysis). Fixed lime percentages at 28 curing days (63%) indicated the high reactivity of EGL ashes in calcium hydroxide pastes due to the pozzolanic reaction. This study demonstrates the possibility of the reuse of ashes from EGLs for the production of environmental-friendly cements.

The Presence of Silica Bodies in the Foliar Epidermis of Zoysiagrass

The presence of silica bodies (SBs) in the foliar epidermis of zoysiagrass (Zoysia spp. Willd.) is a special characteristic, the function of which is not well understood. To quantify the importance of SB, we evaluated foliar SB densities and sizes of five Zoysia species [Z. japonica Steud., Z. matrella (L.) Merr., Z. pacifica (Goudsw.) M. Hotta & S. Kuroki, Z. minima (Colenso) Zotov, and Z. macrostachya Franch. & Sav.] including three ecotypes of each species using tabletop scanning electron microscopy. Our results demonstrated that abaxial SB density was significantly higher (mean: 734.3 mm−2) than that of adaxial SB (mean: 317.7mm−2) in all species. Abaxial SB size was also significantly larger (mean: 80.0 μm2) than that of the adaxial SB (mean: 61.4 μm2) in all species. Zoysia japonica had significantly higher SB density and size than the other tested Zoysia spp. Location‐specific sizes of foliar abaxial SB were identified: large on the midrib, medium on other ribs, and small in the costal zone. These results support the hypothesis that foliar SBs of zoysiagrass function to protect rib bundles and Kranz anatomy from physical damages, and to assist light absorbance for C4 photosynthesis through inhibiting leaves from twisting. Further work assessing SB impact on growth efficiency, survival strategy, and the utility of zoysiagrass is needed.

Micromorfología de la epidermis foliar de cultivares de arroz Venezolano (Poaceae) asociado con el daño mecánico de sogata Tagosodes orizicolus (Homoptera: Delphacidae)

Rice cultivars are affected directly and indirectly by the insect sogata. The mechanical damage or direct loss, is produced after feeding and ovoposition on the young leaves tissues, while the indirect damage is produced after the transmission of the Rice hoja blanca virus. We studied the morpho-anatomic structures associated with the resistance of the mechanical damage produced by the insect, in six rice cultivars, including controls for resistance and susceptibility (Makalioka and Bluebonnet 50), during August 2011, in Fundacion Danac, Venezuela. Samples were taken from leaf 3, where cuticle thickness, presence of macrohair, microhair and silica bodies in the second third of the leaf was evaluated. A significant difference to thickness of the cuticle, the presence of microhair in the leaves, and presence of silica bodies was observed among cultivars, determining a significant correlation among the number of macrohair and microhair in the adaxial leaf blade with the presence of silica bodies, and thickness of the cuticle and number of posed insects. Thickness of the cuticle and presence of silica bodies in the intercostals space of microhair and macrohair showed to be the variables most related to mechanical damage and resistance mechanism.

Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Quesnelia strobilispica Wawra and Wittrockia gigantea (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( Billbergia euphemiae E. Morren and Bromelia antiacantha Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of B. euphemiae and W. gigantea showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species B. euphemiae and the terrestrial species Q. strobilispica have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species Bromelia antiacantha and the epiphytic species W. gigantea also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.

Neglected features of probable taxonomic value in Podostemaceae: The case of Polypleurum

The paper reports on hitherto largely neglected discriminative characters in Polypleurum stylosum, P. elongatum, P. minus, as well as the problematic P. munnarense (Podostemaceae, subfam. Podostemoideae) from India and Sri Lanka. The characters discussed include dimorphism of floriferous and vegetative shoots, leaf dimorphism, presence of peculiar floating trichomes on vegetative leaves, and presence of silica bodies in root and shoot tissue. In addition, anatomical pecularities (well-developed cuticle covering the ovary and ovules, cell inclusions in the form of droplets, and presence of idioblasts with firm inclusions of unknown compounds) and specific morphological features (presence of an apical septum in the gynoecium) are documented. All these features point to different developmental and physiological properties of the species concerned, thus signaling separate evolutionary pathways. They may help to elucidate phylogenetic relationships at various taxonomic levels and may prove useful for the delimitation of the genus.

Silica bodies and their systematic implications in Pteridaceae (Pteridophyta)

Wet ashing was used to study the occurrence of silica bodies in the fern family Pteridaceae. They were recovered in 48 of the 77 species examined. Silica bodies of Pteridaceae are elongate, ranging from 90–1320 × 5–40 µm, linear to elliptic, with blunt or acute apices and smooth to sinuate sides. All previous records of silica bodies and venuloid idioblasts among Pteridaceae that were examined were confirmed by the results of this study, corroborating our assumptions regarding the presence of silica bodies. In contrast, assumptions regarding the absence of silica bodies were incorrect; in many species of Adiantum, for example, silica bodies are present but cannot be seen with the naked eye. Farris optimization demonstrates that the distribution of epidermal silica bodies is homoplastic within Pteridaceae, but that they act as a potential synapomorphies for several different groups within the family. These include the adiantoid clade: Adiantum and the 11 vittaroid genera, and in some pteridoid fern clades such as the sister pair Onychium and Actiniopteris and the genus Pityrogramma. They are also present in Pterozonium brevifrons and some species of the polyphyletic genus Pteris. Among cheilanthoid ferns, they were found in Mildella intramarginalis and two species of Aspidotis. Morphology of silica bodies differs between major lineages, reflecting their independent origins. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161, 422–435.

Leaf anatomical characteristics of Ugandan species of Festuca L. (Poaceae)

The importance of leaf anatomical characters in the taxonomy of Ugandan Festuca species was investigated. In particular, leaf cross sections were studied for variation in disposition of the sclerenchyma tissue to determine whether this is as taxonomically useful as is implied in much of the literature. Also the leaf epidermis was investigated for the presence of diagnostic features. A lot of variation in disposition of sclerenchyma tissue was found in F. abyssinica, which did not support the recognition of F. elgonensis and F. richardii as good species, yet they were described mainly based on leaf anatomy. The ring of sclerenchyma in F. pilgeri and the presence of papillae on the epidermis of F. claytonii supported them to be good species. The presence of silica bodies on the epidermis of Ugandan species of Festuca was investigated for the first time and is confirmed using energy dispersive X-ray analysis. In conclusion, leaf anatomy should be used together with other non-anatomical characters before recognizing species.

Wood anatomy of Polygonaceae: analysis of a family with exceptional wood diversity

Quantitative and qualitative data are presented for woods of 30 species of woody Polygonaceae. Wood features that ally Polygonaceae with Plumbaginaceae include nonbordered perforation plates, storeying in narrow vessels and axial parenchyma, septate or nucleate fibres, vasicentric parenchyma, pith bundles that undergo secondary growth, silica bodies, and ability to form successive cambia. These features are consistent with pairing of Plumbaginaceae and Polygonaceae as sister families. Wood features that ally Polygonaceae with Rhabdodendraceae include nonbordered perforation plates, presence of vestured pits in vessels, presence of silica bodies and dark-staining compounds in ray cells, and ability to form successive cambia. Of the features listed above, nonbordered perforation plates and ability to form successive cambia may be symplesiomorphies basic to Caryophyllales sensu lato. The other features are more likely to be synapomorphies. Wood data thus support molecular cladograms that show the three families near the base of Caryophyllales s.l. Chambered crystals are common to three genera of the family and may indicate relationship. Ray histology suggests secondary woodiness in Antigonon, Atraphaxis, Bilderdykia, Dedeckera, Eriogonum, Harfordia, Muehlenbeckia, Polygonum, and Rumex. Other genera of the family show little or no evidence of secondary woodiness. Molecular data are needed to confirm this interpretation and to clarify the controversial systematic groupings within the family proposed by various authors. Vessel features of Polygonaceae (lumen diameter, element length, density, degree of grouping) show an extraordinary range from xeromorphy to mesomorphy, indicating that wood has played a key role in ecological and habital shifts within the family; the diversity in ecology and habit are correlated with quantitative wood data. © 2003 The Linnean Society of London. Botanical Journal of the Linnean Society, 2003, 141, 25−51.