Sclerenchyma Fibers Research Articles

The Living Fossil Psilotum nudum Has Cortical Fibers With Mannan-Based Cell Wall Matrix.

Cell wall thickening and development of secondary cell walls was a major step in plant terrestrialization that provided the mechanical support, effective functioning of water-conducting elements and fortification of the surface tissues. Despite its importance, the diversity, emergence and evolution of secondary cell walls in early land plants have been characterized quite poorly. Secondary cell walls can be present in different cell types with fibers being among the major ones. The necessity for mechanical support upon increasing plant height is widely recognized; however, identification of fibers in land plants of early taxa is quite limited. In an effort to partially fill this gap, we studied the fibers and the composition of cell walls in stems of the sporophyte of the living fossil Psilotum nudum. Various types of light microscopy, combined with partial tissue maceration demonstrated that this perennial, rootless, fern-like vascular plant, has abundant fibers located in the middle cortex. Extensive immunodetection of cell wall polymers together with various staining and monosaccharide analysis of cell wall constituents revealed that in P. nudum, the secondary cell wall of its cortical fibers is distinct from that of its tracheids. Primary cell walls of all tissues in P. nudum shoots are based on mannan, which is also common in other extant early land plants. Besides, the primary cell wall contains epitope for LM15 specific for xyloglucan and JIM7 that binds methylesterified homogalacturonans, two polymers common in the primary cell walls of higher plants. Xylan and lignin were detected as the major polymers in the secondary cell walls of P. nudum tracheids. However, the secondary cell wall in its cortical fibers is quite similar to their primary cell walls, i.e., enriched in mannan. The innermost secondary cell wall layer of its fibers but not its tracheids has epitope to bind the LM15, LM6, and LM5 antibodies recognizing, respectively, xyloglucan, arabinan and galactan. Together, our data provide the first description of a mannan-based cell wall in sclerenchyma fibers, and demonstrate in detail that the composition and structure of secondary cell wall in early land plants are not uniform in different tissues.

Anatomy of Balkan Amphoricarpos Vis. (Cardueae, Asteraceae) taxa

Anatomical analysis of root, rhizome, leaf, peduncle and inflorescences has been conducted on Balkan Amphoricarpos taxa, A. neumayerianus (Vis.) Greuter subsp. neumayerianus, A. neumayerianus subsp. murbeckii Bosnjak, A. autariatus Blecic & Mayer subsp. autariatus and A. autariatus subsp. bertisceus Blecic & Mayer using light microscopy (LM) and scanning electron microscopy (SEM), in order to examine the anatomical traits of this genus for the first time. All taxa show similar features. Young adventitious roots share a typical structure. Sclerenchyma fibers are present in the center of older root. On the rhizome cross sections, secondary tissues are noticed with wide parenchyma rays which interrupt a-well developed xylem. Rhizomes show eccentric growth. The leaf blade is amphistomatous, with dorsiventral structure. Crystal druses are found in leaf epidermal and mesophyll cells. The peduncle cross sections is characterized by more or less polygonal shape with medullary collateral vascular bundles arranged in a circle, and a few of them outside of the circle, toward to cortex region. Secretory canals are absent. Involucral bracts and paleae are characterised by the presence of multilayer sclerenchyma in the mesophyll. Inflorescence anatomy shows structures commonly described for Asteraceae members. Densely distributed vermiform (lanate) and glandular biseriate trichomes are present on the peduncle and on both leaf sides, but much more on the abaxial. Anatomical uniformity indicates very close relationships between examined taxa regarding conserve nature of the genome of the genus. Obtained characters contribute to the knowledge of the genus Amphoricarpos anatomy.

Silicification of Root Tissues.

Silicon (Si) is not considered an essential element, however, its tissue concentration can exceed that of many essential elements in several evolutionary distant plant species. Roots take up Si using Si transporters and then translocate it to aboveground organs. In some plant species, root tissues are also places where a high accumulation of Si can be found. Three basic modes of Si deposition in roots have been identified so far: (1) impregnation of endodermal cell walls (e.g., in cereals, such as Triticum (wheat)); (2) formation of Si-aggregates associated with endodermal cell walls (in the Andropogoneae family, which includes Sorghum and Saccharum (sugarcane)); (3) formation of Si aggregates in “stegmata” cells, which form a sheath around sclerenchyma fibers e.g., in some palm species (Phoenix (date palm)). In addition to these three major and most studied modes of Si deposition in roots, there are also less-known locations, such as deposits in xylem cells and intercellular deposits. In our research, the ontogenesis of individual root cells that accumulate Si is discussed. The documented and expected roles of Si deposition in the root is outlined mostly as a reaction of plants to abiotic and biotic stresses.

Roots Structure and Development of Austrobaileya scandens (Austrobaileyaceae) and Implications for Their Evolution in Angiosperms

Since the resolution of the ANA grade [Amborellales, Nymphaeales, Austrobaileyales] as sister to all other flowering plants, a few comparative studies of root structure have suggested that some of their anatomical traits could be of importance to understanding root evolutionary development and angiosperm phylogeny. However, there is still a paucity of information on root structure and apical meristems (RAMs) in these lineages and especially the sister to all other Austrobaileyales, Austrobaileya scandens. We used microtome sections and bright field, epifluorescence, laser confocal, and scanning electron microscopy to study adventitious root RAMs and tissues of A. scandens. Our results indicate that root structure is relatively simple in A. scandens. The epidermis has a thick cuticle and lacks root hairs. The stele is typically diarch, or some modification thereof, and surrounded by a cortex differentiated into a uniseriate endodermis, a middle region sometimes packed with starch, some oil cells, and colonized by arbuscular mycorrhizal fungi, and a multiseriate exodermis. Secondary growth produced many vessel elements in the secondary xylem and scattered sclerenchymatous fibers in secondary phloem. The absence of distinct patterning within the RAM and between the RAM and derivative differentiating tissues shows that the RAM is open and characterized by common initials. Roots structure and anatomy of A. scandens are thus essentially similar to some previously described in Amborella or Illicium in the ANA grade and many magnoliids, and suggest that the first woody flowering plants likely had an open RAM with common initials. Their functional and evolutionary significance in woody early-diverging and basal lineages of flowering plants and gymnosperms remains unclear, but they are clearly ancestral traits.

In vitro serial subculture to improve rooting of Eucalyptus urophylla

The aim of this study was to improve the rooting efficiency of Eucalyptus urophylla clones by in vitro reinvigoration/rejuvenation in two clones (02 and 04) from the breeding program of the V&M Florestal company. An in vitro culture began with 200 meristems of each clone, which were excised, disinfected, and inoculated in culture medium. When shoots from these first meristems inoculated reached a height of 3 cm, 100 new meristematic regions of 0.5 cm were isolated and inoculated in culture medium. The other shoots from were inoculated in a rooting medium, where they remained for 30 days. After this period, the plants were acclimatized and used as stock plants for shoot production in a commercial nursery. This process was repeated until the shoots attained an ex vitro rooting rate of more than 80%. After reinvigoration/rejuvenation of clones 02 and 04, the relationship between rooting and the presence of starch and phenolic compounds at the base of the minicuttings was histochemically analyzed. For clone 02, three in vitro subcultures were needed to increase the rooting rate, and for clone 04, only one in vitro subculture was required. In vitro reinvigoration/rejuvenation is a determining factor for greater rooting efficiency of minicuttings of 02 and 04 clones. Production of sclerenchyma fibers around the root vascular cylinder and starch and phenolic compound production are directly related to rooting efficiency.

A silicified Todea trunk (Osmundaceae) from the Eocene of Patagonia

The Osmundaceae family is the sister group to all other extant leptosporangiate ferns. Its rich fossil record has enabled detailed reconstructions of the evolutionary history of the group. Fossil evidence for today’s Southern Hemisphere subtribe Todeinae, however, has been difficult to accumulate, with only two unambiguous fossil occurrences of modern Todea. Here, we describe a silicified Todea stem from the Eocene Laguna del Hunco lagerstatte of Patagonia. The stem contains a heterogeneous outer cortex with distinct fibrous rings surrounding the leaf traces, indicative of subtribe Todeinae; nests of thick-walled fibres associated with departing leaf traces together with the sclerenchymatous pith and with abundant sclerenchyma fibres in the inner stipe cortex enable assignment to Todea. The stem differs from T. tidwellii—the only other known fossil Todea stem described thus far—mainly in lacking sclerenchyma lining the adaxial concavity of the stipe bundle. Co-occurrence with sterile foliage fragments indicates that the stem may belong to Todea amissa, a species that was initially described based on frond compressions from the same deposits. Our finding corroborates the widely disjunct Gondwanan distribution of Todea across the Southern Hemisphere in the past, and provides an impetus to re-assess genetic divergence between the relictual African and Australasian populations of Todea barbara today in order to resolve the evolutionary history of the group more clearly. Finally, this first report of structurally preserved plant remains from Laguna del Hunco highlights the thus far untapped potential for anatomical preservation in this important fossil lagerstatte.

Rice Homeobox Protein KNAT7 Integrates the Pathways Regulating Cell Expansion and Wall Stiffness.

During growth, plant cells must coordinate cell expansion and cell wall reinforcement by integrating distinct regulatory pathways in concert with intrinsic and external cues. However, the mechanism underpinning this integration is unclear, as few of the regulators that orchestrate cell expansion and wall strengthening have been identified. Here, we report a rice (Oryza sativa) Class II KNOX-like homeobox protein, KNOTTED ARABIDOPSIS THALIANA7 (KNAT7), that interacts with different partners to govern cell expansion and wall thickening. A loss-of-function mutation in KNAT7 enhanced wall mechanical strength and cell expansion, resulting in improved lodging resistance and grain size. Overexpression of KNAT7 gave rise to the opposite phenotypes, with plants having weaker cell walls and smaller grains. Biochemical and gene expression analyses revealed that rice KNAT7 interacts with a secondary wall key regulator, NAC31, and a cell growth master regulator, Growth-Regulating Factor 4 (GRF4). The KNAT7-NAC31 and KNAT7-GRF4 modules suppressed regulatory pathways of cell expansion and wall reinforcement, as we show in internode and panicle development. These modules function in sclerenchyma fiber cells and modulate fiber cell length and wall thickness. Hence, our study uncovers a mechanism for the combined control of cell size and wall strengthening, providing a tool to improve lodging resistance and yield in rice production.

KARAKTERISASI SIMPLISIA SKRINING FITOKIMIA DAN UJI TOKSISITAS EKSTRAK ETANOL HERBA BINTARO (Cerbera manghas L.) TERHADAP Artemia salina Leach

The use of anticancer chemotherapy with chemicals has not given optimal results because the drug does not work specifically, in addition to attacking cancer cells it also damages normal cells. Bintaro (Cerbera mangha L.) is a wild plant that contains secondary metabolites which have been shown to have a wide range of therapeutic applications. Several studies have stated that Bintaro has activities as aanti cancer. The purpose of this researchto know the characteristics of Bintaro herb simplicia (Cerbera manghas L.) which can be determined using the procedures listed in the Materia Medika Indonesia book, knowing the class of secondary metabolites contained in the ethanol extract of bintaro herbs (Cerbera manghas L.), andknowing the level of toxicity of the ethanol extract of the herb bintaro (Cerbera manghas L.). The method used in this research is experimental with the post-test only controlled group design. The results of the characterization on the organoleptic test of Bintaro herb simplicia, namely the leaves are dark brown, the taste is slightly bitter then bitter, the stems are dark brown and shrinking, the smell is distinctive and tasteless, and the flowers are dark brown, characteristic odor and tasteless, after being ground to a powder. dark brown. The results of the microscopic test, the leaf herb simplicia samples obtained fragments, namely diasitic type stomata, spiral vessel fragments and upper epidermis fragments with palisade cells. As for the stem herbs, there were tissue fragments of sclerenchyma fibers, vessel fragments, parenchymal fragments with clumps of brown secretions. Sclereid fragments were found in the floral herb samples.6%, for determination of water-soluble extract content obtained = 20.06%, ethanol soluble extract content = 2.18%, total ash content = 12.62%, acid insoluble ash content = 6.11%. positive bintaro herbs contain compounds of alkaloids, flavonoids, steroids, tannins and saponins. From the calculation of the LC50 value, it can be concluded that the entanol extract of the Bintaro herb is included in the very toxic category with a value ofLC50 < 30 g/mlthat is9.35g/mL.

Novel Insight into the Separation and Composite Utilization of Sclerenchyma Fiber Bundles of Willow Bark

The bark from fast-growing willow crops contains long and strong sclerenchyma fiber bundles, which could potentially replace the pulp and annual plant fibers currently used to reinforce green polymer composites. Here we successfully demonstrate the isolation of fiber bundles of willow bark with a simple alkali treatment under much milder conditions than what pulp fiber separation requires. The fiber bundles separated had hydrophobic surfaces, which made them compatible with polymers, in this case with polylactic acid, without using any additives. The most hydrophobic fiber bundles of willow bark provided the strongest and toughest composites, superior to the corresponding isotropic composites of pulp and flax fibers. Integration of the fiber bundle isolation with a prior recovery of hot water extractable aromatics from the bark and further processing of the debarked willow stems into bioethanol and lignin, for example, could make the full valorization of the willow biomass feasible.

Ecological anatomy of Eugenia punicifolia (Kunth) DC. (MYRTACEAE) in the restinga region,state of Ceará

Abstract The species Eugenia punicifolia (Kunth) DC. (myrtle) occurs in the coastal region of the state of Ceará and has ecological and medicinal importance. This study aimed to characterize the leaf anatomy of myrtle (E. punicifolia) in the rainy and dry seasons, as well as in the sun and shade in the restinga region of the state of Ceará and to contribute to the understanding of the morphoanatomic variations in response to the natural conditions of the occurrence of this species. For this, collections of fully expanded leaves were performed at the Botanical Park of Ceará and fixed in FAA70, being replaced by 70% ethanol after 24 hours. The usual anatomical procedures were then performed in order to qualitatively and quantitatively analyze the leaf blade, petiole and epidermis structures. As a result, it was found that myrtle has xeromorphic characteristics such as thick cuticle, hypoestomatic leaf and sclerenchyma fibers in the median vein vascular bundles. It was concluded that E. punicifolia has great plasticity to adjust well under the analyzed conditions.

Comparative vegetative anatomy and mycorrhizal morphology of three South Indian Luisia species (Orchidaceae) with the note on their epiphytic adaptations

The anatomical characteristics of the vegetative structures and mycorrhizal morphology of Luisia pulniana Vatsala, Luisia tenuifolia Blume and Luisia tristis Hook.f. belonging to the subfamily Epidendroideae (Orchidaceae) were investigated. Luisia species have amphistomatic leaves covered by a thick cuticle, paracytic stomata, and homogenous mesophyll containing raphides, silica bodies, water-storage cells and collateral vascular bundles. The leaf sheath has an upper epidermis of conical papillate shaped cells, homogenous mesophyll, water storage cells, raphides and sclerenchymatous fibers. The process of stem thickening through cortical proliferation was observed for the first time in Luisia species. The uniseriate epidermis is dimorphic in L. pulniana stem. The stem cortex is parenchymatous comprising of fibrous idioblasts. The ground tissue is parenchymatous (L. pulniana) or sclerenchymatous (L. tenuifolia, L. tristis) containing scattered collateral vascular bundles. Xylem and phloem capped by sclerenchymatous patches. The root hairs are restricted to root regions attached to the substratum. Velamen 2–4 layered, exodermal cells with greatly thickened outer tangential walls, cover cells present. Endodermis O-thickened, vascular cylinders 15–23 arched. Mycorrhizal fungi entered roots through the root hairs and formed pelotons in the root cortex. The anatomical characteristics varied significantly among the Luisia species. Some of these anatomical features relate Luisia with epiphytic and xerophytic habitats.

SECONDARY WALL ASSOCIATED MYB1 is a positive regulator of secondary cell wall thickening in Brachypodium distachyon and is not found in the Brassicaceae.

Grass biomass is comprised chiefly of secondary walls that surround fiber and xylem cells. A regulatory network of interacting transcription factors in part regulates cell wall thickening. We identified Brachypodium distachyon SECONDARY WALL ASSOCIATED MYB1 (SWAM1) as a potential regulator of secondary cell wall biosynthesis based on gene expression, phylogeny, and transgenic plant phenotypes. SWAM1 interacts with cellulose and lignin gene promoters with preferential binding to AC-rich sequence motifs commonly found in the promoters of cell wall-related genes. SWAM1 overexpression (SWAM-OE) lines had greater above-ground biomass with only a slight change in flowering time while SWAM1 dominant repressor (SWAM1-DR) plants were severely dwarfed with a striking reduction in lignin of sclerenchyma fibers and stem epidermal cell length. Cellulose, hemicellulose, and lignin genes were significantly down-regulated in SWAM1-DR plants and up-regulated in SWAM1-OE plants. There was no reduction in bioconversion yield in SWAM1-OE lines; however, it was significantly increased for SWAM1-DR samples. Phylogenetic and syntenic analyses strongly suggest that the SWAM1 clade was present in the last common ancestor between eudicots and grasses, but is not in the Brassicaceae. Collectively, these data suggest that SWAM1 is a transcriptional activator of secondary cell wall thickening and biomass accumulation in B. distachyon.

In-situ Observation on the Morphological Behavior of Bamboo under Flexural Stress with Respect to its Fiber-foam Composite Structure

An in-situ observation on the morphological behavior of bamboo’s fiber-foam composite structure under flexural stress was conducted, and the respective contribution of parenchymatous tissues and sclerenchyma fibers to the flexural ductility of bamboo was evaluated. Fibers or parenchymatous cells at the bottom suffered tensile stress during bending process, where initial microcracks occurred. The results suggested that the bottom parenchymatous tissues experienced a perforative tear along the loading direction, while fibers continued to stretch until several fibrous tensile failure cracks were observed. The subsequent crack growth mode was similar to that of the horizontal crack transmission that began when it reached fibers or somewhere between fibers, until another weak load-bearing point appeared, and then it expanded up through parenchymatous tissues. As a whole, the crack acted ladder-like in its growth, and the propagation paths were not restricted to a coherent one. Images of the morphological changes of the upper parenchymatous tissues and sclerenchyma fibers, which suffered compressive stress during bending process, indicated that parenchymatous tissues and sclerenchyma fibers made different contributions to the flexural ductility of bamboo. Sclerenchyma fibers supplied deformation resistance for bamboo’s macroscopic deformation, while parenchymatous tissues offered deformation space due to the variation of cellular morphology and location.

In-situ observation on the morphological behavior of bamboo under flexural stress with respect to its fiber-foam composite structure

An in-situ observation on the morphological behavior of bamboo’s fiber-foam composite structure under flexural stress was conducted, and the respective contribution of parenchymatous tissues and sclerenchyma fibers to the flexural ductility of bamboo was evaluated. Fibers or parenchymatous cells at the bottom suffered tensile stress during bending process, where initial microcracks occurred. The results suggested that the bottom parenchymatous tissues experienced a perforative tear along the loading direction, while fibers continued to stretch until several fibrous tensile failure cracks were observed. The subsequent crack growth mode was similar to that of the horizontal crack transmission that began when it reached fibers or somewhere between fibers, until another weak load-bearing point appeared, and then it expanded up through parenchymatous tissues. As a whole, the crack acted ladder-like in its growth, and the propagation paths were not restricted to a coherent one. Images of the morphological changes of the upper parenchymatous tissues and sclerenchyma fibers, which suffered compressive stress during bending process, indicated that parenchymatous tissues and sclerenchyma fibers made different contributions to the flexural ductility of bamboo. Sclerenchyma fibers supplied deformation resistance for bamboo’s macroscopic deformation, while parenchymatous tissues offered deformation space due to the variation of cellular morphology and location.

Comparative leaf morpho-anatomy of six species of Eucalyptus cultivated in Brazil

The present work provides a comparative account of the morpho-anatomy of six species of Eucalyptus, namely E. badjensis Beuzev. & Welch, E. benthamii Maiden & Cambage, E. dunnii Maiden, E. grandis W.Hill, E. globulus Labill. and E. saligna Sm., Myrtaceae. Leaf samples of these six species were investigated by light and scanning electron microscopy. The observed microscopic features that can be useful in the identification and quality control of the studied species include the morphology of epicuticular waxes, presence of prismatic crystals on the leaf surface, leaf midrib shape and arrangement of its vascular system, and the presence or absence of the sclerenchymatous fiber caps in the vascular bundle.

Unveiling 3D physicochemical changes of sugarcane bagasse during sequential acid/alkali pretreatments by synchrotron phase-contrast imaging

Several pretreatment strategies focus on the removal of a significant part of lignin from plant cell walls, as it is considered the main barrier to the process of deconstructing biomass to simple sugars by hydrolytic enzymes. The ability to chemically differentiate and spatially locate lignins across cell walls provides an important contribution to the effort to improve these processes. Here, we present a novel approach using synchrotron phase-contrast tomography to probe the physicochemical features of plant cell walls. In addition to the 3D cellular architecture, the distribution of dense packed lignin–carbohydrate complexes (or, simply dense lignin) over larger regions and within cell walls has been successfully provided. We examined in particular the effect of the sequential H2SO4 and NaOH pretreatment on sugacane bagasse. Our results revealed that aggregates of dense lignin form elongated 3D structures in cell corners (CC) following the orientation of the sclerenchyma fibers; a remarkable result in the light of the conventional perception that lignin particles are discrete and roughly spherical. After the acid pretreatment, a considerable fraction of the dense lignin primarily located in CCs was removed; and it was further dissolved with the subsequent alkali treatment. Unexpectedly, the two-step pretreatment did not contribute to the cellulose accessibility in terms of available surface area and porosity. This study provides new insights into the underlying mechanisms of biomass deconstruction by pretreatments; and the approach established here can be extended to other systems relevant to the bioenergy and biotechnology arenas.

Elucidating wood decomposition by four species of Ganoderma from the United States

The laccate (shiny or varnished) Ganoderma contain fungi that are important wood decay fungi of living trees and decomposers of woody debris. They are also an important group of fungi for their degradative enzymes and bioprocessing potential. Laboratory decay microcosms (LDMs) were used to study the relative decay ability of G anoderma curtisii, Ganoderma meredithiae, Ganoderma sessile, and G anoderma zonatum, which are four commonly encountered Ganoderma species in the U.S., across four wood types (Pinus taeda, Quercus nigra, Q uercus virginiana, and Sabal palmetto). Generally, all Ganoderma species were able to decay all types of wood tested despite not being associated with only certain wood types in nature. G. sessile, on average caused the most decay across all wood types. Among the wood types tested, water oak (Q. nigra) had the most mass loss by all species of Ganoderma. Scanning electron microscopy was used to assess micromorphological decay patterns across all treatments. All Ganoderma species simultaneously decayed wood cells of all wood types demonstrating their ability to attack all cell wall components. However, G. zonatum caused selective delignification in some sclerenchyma fibers of the vascular bundles in palm (S. palmetto) as well as in fibers of water oak. In addition, G. zonatum hyphae penetrated fibers of palm and oak wood causing an unusual decay not often observed in basidiomycetes resulting in cavity formation in secondary walls. Cavities within the secondary walls of fibers gradually expanded and coalesced resulting in degradation of the S2 layer. Differences in colony growth rates were observed when Ganoderma species were grown on medium amended with water soluble sapwood extracts from each wood type. G. meredithiae had enhanced growth on all media amended with sapwood extracts, while G. curtisii, G. sessile and G. zonatum had slower growth on loblolly pine extract amended medium.

Extreme tooth enlargement in a new Late Cretaceous rhabdodontid dinosaur from Southern France

Rhabdodontidae is a successful clade of ornithopod dinosaurs, characteristic of Late Cretaceous continental faunas in Europe. A new rhabdodontid from the late Campanian, of southern France, Matheronodon provincialis gen. et sp. nov., is characterized by the extreme enlargement of both its maxillary and dentary teeth, correlated to a drastic reduction in the number of maxillary teeth (4 per generation in MMS/VBN-02-102). The interalveolar septa on the maxilla are alternately present or resorbed ventrally so as to be able to lodge such enlarged teeth. The rhabdodontid dentition and masticatory apparatus were adapted for producing a strict and powerful shearing action, resembling a pair of scissors. With their relatively simple dentition, contrasting with the sophisticated dental batteries in contemporary hadrosaurids, Matheronodon and other rhabdodontids are tentatively interpreted as specialized consumers of tough plant parts rich in sclerenchyma fibers, such as Sabalites and Pandanites.

Fiber properties of axis and scale of eleven different coniferous cones

Fiber properties of eleven different coniferous cones, growing naturally in Turkey, were studied. Axis and scales of cones were analyzed separately. The slenderness, flexibility, and Runkel ratios were derived from measured fiber dimensions. Fiber length and fiber width of cones were between 0.93mm and 1.87mm, 16.6μm and 32.2μm, respectively. The longest fiber length was determined with 1.87mm in Pinus pinea cone axis fibers. Also, the widest fiber (32.2μm) and the widest lumen (20.0μm) were found in Abies equi-trojani cone scale fibers. The thickest cell wall (8.40μm) were found in Pinus sylvestris cone axis fibers. The sclerenchyma fibers, which were shorter and wider than fibers, were observed both in scale and axis of all cones. In general, cone axis fibers had lower slenderness and Runkel ratios and higher flexibility ratio than those of cone scale fibers. These results indicated that fiber properties of coniferous cones showed similarities with fibers of hardwood and nonwood species.

Tropical forages: morphoanatomy of plants grown in areas with the death of pasture syndrome.

Roots and leaves of Panicum maximum Tanzânia, Mombaça and Massai; Urochloa brizantha Piatã, Marandu and Xaraés; Urochloa humidicola Llanero; Urochloa ruziziensis Ruzizienses; Urochloa hybrida Mulato II and Cynodon nlemfuensis Estrela-roxa were analyzed, seeking to identify characters for better adaptation to the environment that may interfere with digestibility of tissue from the point of view of the rumen in cattle. Were planted ten cultivars in a completely randomized blocks with three repetitions. Was collected vegetative material, which histological slides were prepared from middle third of the sections of roots and leaves. Were observed differences (p>0.05) in the roots: higher volume of epidermal cells (28.62 µm) and overall diameter (1926.41 µm) of Llanero; thicker vascular cylinder (975.09 µm) and more protoxylem (42.25) in Estrela-roxa and occurrence of aerenchyma in cultivars Piatã, Mulato II, Xaraés, Massai, Llanero and Estrela-roxa; Were found higher proportions of bulliform cells in the leaves (121.07 µm) and thicker leaf mesophyll in U. humidicola Llanero (263.63 µm); higher proportion of sclerenchyma fibers in Xaraés and Marandu; lower results for amount of fibers in P. maximum Massai. We conclude that the cultivars Estrela-roxa, Llanero and Massai have greater adaptability to the environment and better nutritional quality.