Anatomy and Properties of Bamboo.pdf - Anatomy and...

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Anatomy and Properties of BambooW. LieseInstitute of Wood Biology and Wood Preservation of the FederalResearch Centre for Forestry and Forest Products,Leuschnerstr, 91, 2050 Hamburg, Federal Republic of GermanyAbstractThe numerous alternativesin the use ofbamboo dependon the unique properties ofits culm. In order to understand the anatom-ical and chemicalmake-up and its ensuingmechanical properties,an attempt has beenmade to summarizethe accessible informa-tion.AnatomyGross anatomy:The properties of theculm are determined by its anatomical struc-ture. The culm consists of internodes andnodes. At the internodes, the cells are axiallyoriented, whereas at the nodes, cells providethe transverse interconnections. No radial cellelements, such as rays, exist in the inter-nodes. Within the nodes an intensive branch-ing of the vessels occurs. These also bendradially inward and provide transverse con-duction through the nodal diaphragms, sothat all parts of the culm are interwoven. Theouter part of the culm is formed by two epi-dermal cell layers, the inner appearing thickerand highly lignified. The surface of outermostcells are covered by a cutinized layer with awax coating. The inner parts of the culm con-sist of numerous sclerenchyma cells. Anylateral movement of liquids is therefore muchhindered. Pathways for penetration are thusonly the cross ends of the culm and to a muchsmaller extent the sheath scars around thenodes.The gross anatomical structure of a trans-verse section of any culm internode is deter-mined by the shape, size, arrangement andnumber of the vascular bundles. They areclearly contrastedb ythe darker coloredsclerenchymatous tissue against the paren-chymatous ground tissue. At the peripheralzone of the culm the vascular bundles aresmaller and more numerous, in the innerparts larger and fewer (Figs. 1, 2). Within theculm wall the total number of vascularbundles decreases from bottom towards thetop, while their density increases at the sametime. The culm tissue is mostly parenchymaand the vascular bundles which are com-posed of vessels, sieve tubes with companioncells and fibres. The totalculmcomprisesabout50%parenchyma,40%fibre,and10% conducting tissues (vessels and sievetubes) with some variation according tospecies.The percentage distribution andorientation of cells show a definite patternwithin the culm, both horizontally and ver-tically. Parenchyma and conducting cells aremore frequent in the inner third of the wall,whereas in the outer third the percentage offibers is distinctly higher. In the vertical direc-tion the amount of fibres increases frombottom to top and that of parenchymadecreases (Fig. 3) The common practice ofleaving the upper part of a cut culm unused inthe forest is therefore a waste with regard toits higher fibrecontent.

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Term
Fall
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Strength of materials, bamboo

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