Ø In some plants, phloem fibres are very long. Through bi-directional elongation, fibres join other fibres initiated individually in other stem levels, thus forming the bundles. Phloem is the complex tissue, which acts as a transport system for soluble organic compounds within vascular plants.. (C) Phloem fibre: The fibre, which occurs in association with phloem, is referred to as phloem fibre. Ø Phloem fibres are also called as bast fibres. It is responsible for transporting food from the leaves to the other parts of the plant. Topic 3 Part I Phloem fibers is the elongated sclerenchyma cells in the phloem, and is responsible for providing tension strength without limiting flexibility. Phloem-It consists of four of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma. Ø Septate fibres occur in the phloem of Vitis (Grapes). The extraxylary fibre subdivides into three kinds like: Phloem fibres: These occur in the primary and secondary phloem of vascular plant tissues, and also called as “Bast fibres”. 9. Phloem fibers is plant fibre collected from the phloem (the "inner bark", sometimes called "skin") or bast … Ø They are long, soft and silky in appearance, hence have immense economic importance. INTRODUCTION. Based on the origin, two types of phloem occurs (A). Unlike the xylem, phloem conducts in both directions. Primary phloem fibres of Linum (flax) are of economic importance. In some species, sclereids and fibres are absent from the functioning phloem, but differentiate at a later stage. Phloem fibres are flexible long cells that make up the soft fibres… Shape, structure, content and arrangement: The fibres are … It was believed for decades that while plant fibres grow by intrusive apical elongation they deposit secondary cell walls in the older, central parts of the cell (Esau 1977; Fahn 1990). Bundle structure of primary and secondary phloem fibres was examined in fibre-enriched peels of mature stems after fixing in 80 % ethanol and partial maceration (1.0 % Macerozyme, Serva, overnight) and clearing the samples by boiling for 1 min in concentrated lactic acid. The key determinant of final bundle structure, both for primary and secondary phloem fibres, is intrusive growth. 3.17). The multi-layered phloem fibre structure in Mallotus japonicus was similar to the cell-wall structure of tension wood fibres with a multi-layered structure. Open in new tab Download slide. Phloem (or bast) fibres are a common source of commercial fibres and are produced from several plant species, including Corchorus capsularis and C. olitorius (jute), Linus usitatissimum (flax), Boehmeria nivea (ramie) and others (Kirby, 1963).In these dicotyledonous plants, the commercial fibres are sclerenchyma cells with copious secondary wall thickening (Kundu, 1944; Fahn, 1990). It derives wholly from the ground meristem tissue, whose structure, shape and composition are somewhat similar to the xylary fibre. Other articles where Phloem parenchyma is discussed: phloem: Phloem parenchyma cells, called transfer cells and border parenchyma cells, are located near the finest branches and terminations of sieve tubes in leaf veinlets, where they also function in the transport of foods. Phloem fibre elongation and cell wall thickening do not coincide. Primary Phloem (B). Fibres often alternate, in bands, with conducting cells, for example in Tilia and various Malvaceae (Fig. Phloem contains living tissues except for fibres … Sometimes the terms bast fibre or bass fibre or basswood or bast wood fibre are synonymously used to mean phloem fibre. While the phloem ages and moves away from the cambium, its structure dramatically change, and typically axial parenchyma cells enlarge (Figures 4a and b, 6c), divide, and store more ergastic contents toward the nonconducting phloem. Phloem Definition. Classification of Phloem. Fig.