sieve tube

sieve tube
1. a vertical series of sieve cells in the phloem, specialized for the conduction of food materials.
2. a single sieve cell.

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▪ plant structure
      in flowering plants, elongated living cells (sieve-tube elements) of the phloem, the nuclei of which have fragmented and disappeared and the transverse end walls of which are pierced by sievelike groups of pores (sieve plates). They are the conduits of food (mostly sugar) transport.

      In nonangiospermous vascular plants—e.g., gymnosperms and ferns—rows of sieve cells, showing more primitive structural features, perform the same function. Sieve-tube elements are almost always adjacent to nucleus-containing companion cells, which have been produced as sister cells with the sieve element from the same mother cell. Companion cells apparently function with the enucleate sieve-tube elements and die when they break down. The sieve cells of nonangiospermous vascular plants lack true companion cells, although other adjacent cells may serve a similar function.

      The small pores of sieve cells and the larger ones of sieve elements are traversed by strands of cytoplasm called P-protein. It is not known whether P-protein is active in transport or merely serves as a seal against leakage in case of injury. See also phloem.

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Universalium. 2010.

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Look at other dictionaries:

  • sieve tube — n. Bot. a longitudinal tube in the phloem of flowering plants, consisting of a connected series of individual cells (sieve cells) and serving to conduct organic food materials through the plant …   English World dictionary

  • sieve tube — sieve′ tube n. Bot. bot a vertical series of cylindrical cells in the phloem, specialized for the conduction of food materials • Etymology: 1870–75 …   From formal English to slang

  • sieve tube — noun tube formed by cells joined end to end through which nutrients flow in flowering plants and brown algae • Hypernyms: ↑vascular tissue • Part Holonyms: ↑phloem, ↑bast * * * noun : a tube consisting of an end to end series of thin walled… …   Useful english dictionary

  • sieve tube — /ˈsɪv tjub/ (say siv tyoohb) noun a longitudinal, food conducting, tubelike structure present in the phloem of angiosperms composed of sieve tube elements (cells containing cytoplasm but not nuclei) placed end to end with perforations (sieve… …  

  • Sieve tube element — in the plant, sieve elements are living cells. They are thick and circular and can be different colours.At the interface between two sieve tube members in angiosperms are sieve plates, pores in the plant cell walls that facilitate the movement of …   Wikipedia

  • sieve-tube element — noun or sieve tube member : a thin walled elongated living cell that has no nucleus at maturity, is continuous with other similar cells by protoplasmic strands which pass through the perforations of specialized sieve plates, prob. functions… …   Useful english dictionary

  • sieve-tube member — noun see sieve tube element …   Useful english dictionary

  • sieve tube — A tube within the phloem tissue of a plant, composed of joined sieve elements …   Glossary of Biotechnology

  • sieve tube — The structure within the phloem of higher plants that is responsible for transporting organic material (sucrose, raffinose, amino acids, etc.) from the photosynthetic tissues (eg. leaves) to other parts of the plant. Made up of a column of cells… …   Dictionary of molecular biology

  • sieve tube — noun Date: 1875 a tube consisting of an end to end series of thin walled living plant cells characteristic of the phloem and held to function chiefly in translocation of organic solutes …   New Collegiate Dictionary

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