Bark Anatomy of Podocarpus elongatus (Ait) L.Herit and Screening of Phytochemical Constituents with Antimicrobial Potential

Background: Conifer Podocarpus elongatus belongs to the family Podocarpaceae and some species of Podocarpus are used in traditional medicine. The present study was undertaken to study the anatomical features of the bark of Podocarpus elongatus (Ait) L.Herit. The study was also focused on the antimicrobial activity and phytochemicals present in the bark extract. Methods: The bark was collected from the P. elongatus from Nilgiri Hills of Ooty, Tamil Nadu. The anatomical structures of the bark were elucidated macroscopically and microscopically by using the sectioning techniques. The phytochemical examination was done to confirm the presence of phytochemical components in the methanol extract. The antimicrobial activity was also studied based on the zone of inhibition. Result: The surface of the bark was highly distinguished from other related species, in the pattern of colour, stripes and thickness. Microscopical study envisaged that periderm is characterised by well distinct, continuous structures of the branchy sclereids with thick undulate, continuous segments that have been originated from a deeper cortex. TLS and RLS of the bark view elucidated that the phloem component appeared to be a vertical plane in the fibres. Phloem rays were found as uniseriate with wide sieve cells. Furthermore, antimicrobial activities of the bark exhibited potential effects against examined bacterial and fungal strains.

Bark Effects on Stemflow Chemistry in a Japanese Temperate Forest II. The Role of Bark Anatomical Features

A fraction of rainfall drains to the soil surface down tree stems (as “stemflow”), and the resulting stemflow waters can be highly enriched with dissolved nutrients due to prolonged bark contact. To date, stemflow chemistry has been examined mostly in regards to the external morphology of the bark, while its relationship with bark anatomy has received little attention. Arguably, this represents a major knowledge gap, because bark anatomical traits are linked to the storage and transport of soluble (and insoluble) organic materials, and control the proximity of these materials to passing stemflow waters. To initiate this line of investigation, here, we examine bark-water leaching rates for common leachable macronutrient ions (Mg2+, Ca2+, and K+) across six different tree species with varying bark anatomical traits (four deciduous broadleaved and two evergreen coniferous species). These different bark types were subjected to laboratory experiments, including observations of bark anatomy and soaking experiments. Laboratory-derived estimates of leaching rates for Mg2+, Ca2+, and K+ were then analyzed alongside bark anatomical traits. Leaching rates of Mg2+ and Ca2+ appear to be controlled by the thickness of the rhytidome and periderm; while K+ leaching rates appeared to be driven by the presence of cellular structures associated with resource storage (parenchyma) and transfer (sieve cells). Other species-specific results are also identified and discussed. These results suggest that the anatomical features of bark and the concentration of leachable macronutrient ions in stemflow are related, and that these relationships may be important to understand nutrient cycle through the bark. We also conclude that future work on the mechanisms underlying stemflow solute enrichment should consider bark anatomy.

A COMPREHENSIVE STUDY ON THE BARK ANATOMY, PHYTOCONSTITUENT AND DETERMINATION OF ANTIMICROBIAL EFFICACY OF ARAUCARIA COOKII

Araucaria cookii, a peculiar ornamental exotic conifer found in India and prevalent in varied European countries and the United States. These have exhibited diverse therapeutic properties, but still evidently unclear. Bark anatomy has been contributed significantly in the analytical observation of its potential and found very scanty in published literatures. In present study, westudiedthe anatomical observation of the bark of A. cookii, and identify the anti-microbial activities of methanol bark extract of A.cookii. The bark of A. cookii was collected from the A. cookii from Nilgiri Hills of Ooty Tamil Nadu. The anatomical structures of the bark were elucidated, based on the pattern of the bark, macroscopically and microscopically by using the techniques such as tangential longitudinal section (TLS) and radial longitudinal section (RLS). The phytochemical examination of the methanol bark extract was done to confirm the presence of phytochemical components. The antimicrobial activity of the bark extract was also studied based on the zone of inhibition.The phytochemical constituents detected were presumed to be responsible factors for its medicinal features. Thus, our results showed that the bark of A.cookiicould act as a possible antimicrobial natural source against probable infectious pathogens.

Phylogenetic placement of enigmatic Astianthus (Bignoniaceae) based on molecular data, wood and bark anatomy

Background: Astianthus is a monospecific arborescent genus of Bignoniaceae that occur in the Pacific Coast of central Mexico and northern Central America, where it grows in dense populations along riversides. Its phylogenetic placement has remained controversial since Astianthus has unusual morphological characters such as a four-loculed ovary, and simple, pulvinate, verticillate leaves. Methods: Here we used three plastid markers ndhF, rbcL, and trnL-F, wood, and bark anatomical data to investigate the phylogenetic placement of Astianthus and assign it to one of Bignoniaceae’s main clades. Results: Our molecular phylogenetic analyses indicated that Astianthus belongs in tribe Tecomeae s.s., where other charismatic Neotropical Bignoniaceae genera such as Campsis and Tecoma are currently placed. Wood and bark anatomy support this placement, as Astianthus reunites a unique combination of features only known from members of Tecomeae s.s., such as storied axial parenchyma, the co-occurrence of homo- and heterocellular rays, septate fibers, and scattered phloem fibers in the bark. Conclusions: The placement of Astianthus within Tecomeae s.s. provides further support to previous proposals for the Neotropical origin of this Pantropical tribe.

Wood and bark anatomy of South African Picrodendraceae with systematic and ecological implications

Wood and bark structure of Androstachys johnsonii and Hyaenanche globosa (Picrodendraceae) is described. Two species share simple perforation plates, minute to small intervessel pits, and nonseptate fibres; these traits also reported in other Picrodendraceae. Androstachys is distinctive in having scanty paratracheal axial parenchyma and uniseriate rays with vessel-ray pits restricted to marginal cells. Bordered pits on fibre walls is an ancestral condition for the African Picrodendraceae. High vessel frequency and vessel grouping in Androstachys can be adaptive for semi-arid climate with wet summer. Both genera share the subepidermal phellogen initiation and the presence of thick-walled fibers and sclereids in secondary phloem. In Hyaenanche, the bark is dilated by stretching and divisions of parenchyma cells with formation of pseudocortex. Androstachys shows no ray dilatation, but sclerification of its parenchyma can make substantial contribution in bark expansion. Abundant trichomes on epidermis of young shoots of Androstachys are presumably involved in the water uptake from mists.

How does bark contribution to postural control change during tree ontogeny? A study of six Amazonian tree species

Recent works revealed that bark is able to produce mechanical stress to control the orientation of young tilted stems. Here we report how the potential performance of this function changes with stem size in six Amazonian species with contrasted bark anatomy. The potential performance of the mechanism depends both on the magnitude of bark stress and the relative thickness of the bark. We measured bark longitudinal residual strain and density, and the allometric relationship between bark thickness and stem radius over a gradient of tree sizes. Constant tensile stress was found in species that rely on bark for the control of stem orientation in young stages. Other species had increasing compressive stress, associated with increasing density attributed to the development of sclereids. Compressive stress was also associated with low relative bark thickness. The relative thickness of bark decreased with size in all species, suggesting that a reorientation mechanism based on bark progressively performs less well as the tree grows. However, greater relative thickness was observed in species with more tensile stress, thereby evidencing that this reduction in performance is mitigated in species that rely on bark for reorientation.

Mechanical stress in the inner bark of 15 tropical tree species and the relationship with anatomical structure

Recent studies have shown that the inner bark is implicated in the postural control of inclined tree stems through the interaction between wood radial growth and tangential expansion of a trellis fiber network in bark. Assessing the taxonomic extent of this mechanism requires a screening of the diversity in bark anatomy and mechanical stress. The mechanical state of bark was measured in 15 tropical tree species from various botanical families on vertical mature trees, and related to the anatomical structure of the bark. Significant tensile or compressive longitudinal stresses were observed in the stems of most species. Tensile longitudinal stress was observed in various botanical families and was always associated with fibers arranged in a trellis-like structure and strong dilatation of rays. The highest tensile stress was recorded in species with gelatinous fibers forming a treillis. Compressive stress was typically associated with a large amount of sclereids in the bark, supporting the differentiation of sclereids as a potential origin of the generation of longitudinal compressive stresses in bark. In species exhibiting both a fibrous trellis structure and a significant amount of sclereids, the sign of longitudinal stress may depend on the balance between these two mechanisms.