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In plant anatomy
Plant anatomy

Plant Anatomy or phytotomy is the general term for the study of the internal Anatomy of plants. While originally it included plant morphology, which is the description of the physical form and external structure of plants, since the mid Twentieth Century the investigation of plant anatomy is considered a separate, distinct field, and re...
, sieve vascular tissue tube elements, also called sieve tube members, are a type of elongated parenchyma
Parenchyma

Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, from Greek language parenkhuma, visceral flesh, from parenkhein, to pour in beside : para-, beside + en-, in + khein, to pour....
 cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
s in phloem
Phloem

In vascular plants, phloem is the living Biological tissue that carries organic nutrients , particularly sucrose, a sugar, to all parts of the plant where needed....
 tissue. At the ends these cells are connected with other sieve elements, and together they constitute the sieve tube. The main function of the sieve tube is transport of carbohydrate
Carbohydrate

Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components ....
s in the plant (e.g., from the leaves to the fruit
Fruit

The term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. In botany, which is the scientific study of plants, fruits are the ripened Ovary of flowering plants....
s and root
Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
s). Unlike vessel element
Vessel element

A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers....
s, which are elongated cells that transport water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 and mineral
Mineral

A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
s in the xylem
Xylem

In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. The word "xylem" is derived from classical Greek language ????? , "wood", and indeed the best known xylem tissue is wood, though it is found throughout the plant....
/wood that are dead when mature, and represent another kind of vascular tissue
Vascular tissue

Vascular tissue is a complex conducting tissue , formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem....
 in the plant, sieve elements are living cells.






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In plant anatomy
Plant anatomy

Plant Anatomy or phytotomy is the general term for the study of the internal Anatomy of plants. While originally it included plant morphology, which is the description of the physical form and external structure of plants, since the mid Twentieth Century the investigation of plant anatomy is considered a separate, distinct field, and re...
, sieve vascular tissue tube elements, also called sieve tube members, are a type of elongated parenchyma
Parenchyma

Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, from Greek language parenkhuma, visceral flesh, from parenkhein, to pour in beside : para-, beside + en-, in + khein, to pour....
 cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
s in phloem
Phloem

In vascular plants, phloem is the living Biological tissue that carries organic nutrients , particularly sucrose, a sugar, to all parts of the plant where needed....
 tissue. At the ends these cells are connected with other sieve elements, and together they constitute the sieve tube. The main function of the sieve tube is transport of carbohydrate
Carbohydrate

Carbohydrates or saccharides are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy and structural components ....
s in the plant (e.g., from the leaves to the fruit
Fruit

The term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. In botany, which is the scientific study of plants, fruits are the ripened Ovary of flowering plants....
s and root
Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
s). Unlike vessel element
Vessel element

A vessel element is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are typically found in the angiosperms but absent from most gymnosperms such as the conifers....
s, which are elongated cells that transport water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 and mineral
Mineral

A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
s in the xylem
Xylem

In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. The word "xylem" is derived from classical Greek language ????? , "wood", and indeed the best known xylem tissue is wood, though it is found throughout the plant....
/wood that are dead when mature, and represent another kind of vascular tissue
Vascular tissue

Vascular tissue is a complex conducting tissue , formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem....
 in the plant, sieve elements are living cells. They are thick and circular and can be different colours. Sieve tubes are not known as 'Real Cells' as they lack a substantial amount of Cytoplasm.

At the interface between two sieve tube members in angiosperms are sieve plates, pores in the plant cell walls that facilitate the movement of liquid. Neighbouring each of the sieve tube elements is a minimum of one companion cell, connected by plasmodesmata
Plasmodesmata

Plasmodesmata are microscopic channels which traverse the cell wall of plant cells and enable transport and communication between them. Plants having plasmodesmata include the highest derived charophyceans, Charales and Coleochaetales, as well as all embryophytes, better known as land plants....
 (channels between the cells). Sieve tube members have no cell nucleus
Cell nucleus

In cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in all eukaryote cell ....
, ribosome
Ribosome

Ribosomes are complexes of RNA and protein that are found in all cell s. Ribosomes from bacteria, archaea and eukaryotes, the three domains of life on Earth, have significantly different structure and RNA....
s, or a vacuole
Vacuole

A vacuole is a membrane organelle which is present in all eukaryotic cells. Vacuoles are essentially enclosed compartments which are filled with fluid such as water or various enzymes, though in certain cases they may contain solids which have been engulfed....
, the nucleus and ribosomes of its companion cell(s) compensate for this. In leaves
Leaf

In botany, a leaf is an above-ground plant Organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin, to expose the cells containing chloroplast to light over a broad area, and to allow light to penetrate fully into the tissues....
, these cells help in moving the sugar produced by photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
 in the mesophyll tissue into the sieve tube elements. Sieve tubes are mainly to transport sugars and nutrients up and down the plant.

Sieve cells are long, slender, conducting cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
s of the secondary phloem
Phloem

In vascular plants, phloem is the living Biological tissue that carries organic nutrients , particularly sucrose, a sugar, to all parts of the plant where needed....
 that do not form a constituent element of a sieve tube, but which are provided with relatively unspecialized sieve areas, especially in the tapering ends of the cells that overlap those of other sieve cells. They have a narrower diameter and are more elongated compared to sieve tube members, the other kind of sieve elements present in the phloem. Sieve cells are associated with albuminous cells, which lack starch
Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
, thus making it possible to differentiate them from phloem parenchyma
Parenchyma

Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, from Greek language parenkhuma, visceral flesh, from parenkhein, to pour in beside : para-, beside + en-, in + khein, to pour....
.

The forest botanist Theodor Hartig was the first to discover and name these cells as Siebfasern (sieve fibres) and Siebröhren (sieve tubes) in 1837.

See also

  • Phloem
    Phloem

    In vascular plants, phloem is the living Biological tissue that carries organic nutrients , particularly sucrose, a sugar, to all parts of the plant where needed....
  • Vascular tissue
    Vascular tissue

    Vascular tissue is a complex conducting tissue , formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem....


External links


  • - University of Hamburg Department of Biology
  • by Dr. David T. Webb - University of Hawaii