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Search Results: 1 - 10 of 336674 matches for " León H "
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Anatomía del xilema secundario de 14 especies del género PouteriaAubl. (sapotaceae) en Venezuela
León H,Williams J;
Acta Botánica Venezuelica , 2009,
Abstract: wood anatomy of 14 species of the genus pouteria aubl. (sapotaceae) growing in venezuela was studied. the following species were studied: p. amygdalicarpa, p. caimito, p. coriacea, p. cuspidata subsp. dura, p. decorticans, p. egregia, p. eugeniifolia, p. guianensis, p. hispida, p. macrophylla, p. procera, p. reticulata, p. trilocularis and p. venosa. wood description was done according iawacommittee list. an one wayanova and tukey test for multiple comparisons was performed regarding quantitative features. secondary xylem shows homogeneity in pouteria genus; the main distinctive features between species are pore diameter, pit diameter, rays width and number of wide cells in parenchyma bands. according to these features, a dichotomous key was elaborated. pouteria decorticans and p. hispida can only be separated using quantitative features like diameter of intervessel pits. similar case was observed between p. egregia and p. procera, separated by fibre length.
Anatomía ecológica del xilema secundario de un bosque seco tropical de Venezuela
LEóN H,Williams J;
Acta Botánica Venezuelica , 2005,
Abstract: the wood anatomy of 51 trees from el caimital forest were studied from an ecological perspective and were compared with data from other habitats. the features studied were vessel frequency, vessel diameter, vessel element length, perforation plates, intervessel pit size, presence of crystals and silica. vulnerability, mesomorphy and vessels grouping index were calculated. a predominance of characters towards hydraulic efficiency was observed. in accordance with vessel size, vessel number, mesomorphy and vulnerability index, the wood of the studied individuals can be characterized as mesomorphic.
Anatomía del Xilema secundario de diez especies de la familia Bignoniaceae de Venezuela
LEóN H.,Williams J.;
Acta Botánica Venezuelica , 2007,
Abstract: the wood anatomy of ten species of the bignoniaceae family growing in venezuela is presented: crescentia amazonica, jacaranda copaia, j. filicifolia, j. obtusifolia, tabebuia chrysea, t. chrysantha, t. impetiginosa, t. rosea, t. serratifolia and t. stenocalyx. in crescentia amazonica silica bodies in axial parenchyma cells were found. foraminate perforation plates were found in crescentia amazonica and tabebuia rosea. all species have homocelular rays with only procumbent cells except in j. copaia, which has some heterocellular rays. according anatomical features, tabebuia species were distributed in two groups except t. chrysea which has anatomical features of both groups.
Estudio anatómico del Xilema Secundario de 17 especies de la familia Anacardiaceae en Venezuela
LEóN H.,Williams J.;
Acta Botánica Venezuelica , 2003,
Abstract: this paper deals about wood anatomy of seventeen species from anacardiaceae family in venezuela: anacardium excelsum, a. spruceanum, astronium graveolens, a. obliquum, a. ulei, campnosperma gumifera, cyrtocarpa velutinifolia, loxopterygium sagotii, mangifera indica, mauria heterophylla, ochoterenaea colombiana, spondias lutea, s. mombin, rhus striata, tapirira guianensis, t. obtusa and thyrsodium spruceanum. the species were divided in two groups: species with radial gum ducts and species without radial gum ducts. particularly noteworthy is the foraminate perforation plates in mauria heterophylla and thyrsodium spruceanum, reported for the first time in the family, and scalariform perforation plates in tapirira guianensis and t. obtusa, reported for the first time in the genus. adichotomous key is presented for wood identification.
Anatomía de la madera de 13 especies del orden Sapindales que crecen en el Estado Mérida, Venezuela
LEóN H.,Williams J.;
Acta Botánica Venezuelica , 2006,
Abstract: abstract wood anatomy descriptions for 13 species of the sapindales order growing in merida state, venezuela are presented. this includes species from anacardiaceae (astronium graveolens, ochoterenaea colombiana, toxicodendron striatum), burseraceae (bursera simaruba, protium heptaphyllum), hippocastanaceae (billia columbiana), meliaceae (cedrela montana, guarea kunthiana, trichilia hirta), rutaceae (zanthoxylum quinduense, z. melanostictum), sapindaceae (matayba scrobiculata) and staphyleaceae (turpinia occi-dentalis). among the studied families, anacardiaceae and burseraceae show the highest degree of similarity. turpinia occidentalis (staphyleaceae) on the other hand, presents features that are clearly distinctive from the remaining members of sapindales which may represent primitive structures. an identification key with microscopic characteristics is given.
Estudio anatómico de la madera de 21 especies del género Vochysia Poir. (Vochysiaceae)
LEóN H,Williams J;
Acta Botánica Venezuelica , 2005,
Abstract: this paper deals about wood description of 21 species from the genus vochysia. woods of this genus are very homogeneous making the identification using wood features difficult. in all the studied species the same parenchyma types, rays of two distinct sizes, vestured pits and axial canals were observed. in v. lehmanii and v. venezuelana druses in axial canals were observed, and this could be the first report about this crystal type in vochysia and the first report about the presence of crystals in axial canals. in v. cayennensis and v. venezuelana trabeculae were found, and this could be the first report about it.
Análisis preliminar sobre anatomía del le?o de 11 especies de la tribu Heliantheae (Asteraceae) de Los Andes venezolanos
León H,Williams J;
Ernstia , 2007,
Abstract: the secondary xylem anatomy of eleven species of the heliantheae tribe (asteraceae) growing in the venezuelan andes is described. the species described are carramboa badilloi, c. littlei, c. pittieri, c. rodriguezii, c. tachirensis, c. trujillensis, libanothamnus granatesianus, l. neriifolius, l. occultus, montanoa quadrangularis and ruilopezia marcescens. m. quadrangularis is easy to separate from the others because it has septate fibres, exclusively simple perforation plates, pores with mean diameters greater than 100 mm and less than 20 pores/mm2. species from carramboa, libanothamnus and ruilopezia (espeletiinae subtribe) have remarkable similitude among them. the mean features to differentiate them are related with intervessel and ray-vessel pits. ruilopezia have wood anatomical features intermediate between carramboa and libanothamnus. we found sheath cells in c. littlei, c. pittieri, l. granatesianus and m. quadrangularis. the presence of growth rings was observed only in l. occultus. a dichotomous key for wood identification is included.
Anatomía de la madera de siete especies del género terminalia l. En Venezuela
León H,Williams J.;
Ernstia , 2007,
Abstract: the wood anatomy of seven species of terminalia (combretaceae) is described according iawa list for hardwood identification. the studied species were t. amazonia, t. catappa, t. guyanensis, t. oblonga, t. obovata, t. quintalata and t. yapacana. the wood anatomy is very similar among the different species of terminalia and one of the most important features for identification is related with crystals; their presence or absence, localization and crystal type. t. amazonia and t. obovata are not similar in localization and abundance of crystals and for this reason, we did not include t. obovata as a synonym of t. amazonia. only in t. quintalata and t. yapacana, were crystals absent, and the main feature for differentiation it is related to septate fibres: present in t.yapacana and absent in t. quintalata.
Anatomía de la madera de 20 especies de lianas del lote boscoso El Dorado-Tumeremo (estado Bolívar, Venezuela)
León H,Williams J;
Ernstia , 2009,
Abstract: this paper presents the wood anatomy of 19 species of lianes from bolívar state, venezuela. the species studied belong to 12 families: bignoniaceae (2), caesalpiniaceae (2), combretaceae (1), dilleniaceae (2), papilionaceae (3), menispermaceae (3), moraceae (1), nyctaginaceae (1), rhamnaceae (1), sapindaceae (1), ulmaceae (1), verbenaceae. the material was prepared using conventional microtechnique. descriptions were realized according to rules of the iawa. the features found with greatest frequency were crystals (85 %), cambial variants (55 %) and two-sized vessels (50 %). the cambial variant types found were stems with furrowed xylem, concentric phloem, diffuse phloem and compound xylem cylinder. a dichotomous key for identification is presented.
ANATOMíA DE MADERA EN 31 ESPECIES DE LA SUBFAMILIA MIMOSOIDEAE (LEGUMINOSAE) EN VENEZUELA
León H.,Williams J.;
Colombia Forestal , 2008,
Abstract: this paper is about the wood anatomy of 31 species, belonging to 17 genera, of the mimosoideae subfamily (leguminosae), proceeding from different geographical regions of venezuela. for each species, one to five individuals were studied. the descriptions were realized according to the iawa committee(1989). the studied species may be divided in two groups according to the presence or absence of septate fibers. all species of inga showed septate fibers, whereas albizia and enterolobium included species with septate fibers and also species with non-septate fibers. the quantitative characteristics of the vessels and the width of rays showed sufficient variation as to be considered important characteristics from ataxonomic point of view. the most common parenchyma type was vasicetric, aliform and confluent. in calliandra laxa, prosopis juliflora and zygia longifolia the main parenchyma type was in wide bands; whereas in cedrelinga cateniformis, the main parenchyma type was thin vasicentric. all species studied, with the exception of cedrelinga cateniformis, presented prismatic crystals in the parenchymatous axials cells. in spite of finding certain anatomical uniformity, it was possible to elaborate a key for the identification of the studied species.
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