Name the tissue surrounding the vascular bundle
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phloem ,xylem are the 2 tissues
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A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in vascular tissue, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition will include supporting and protective tissues. Also, it is a vein in the leaf that contains conducting tissues.
The xylem typically lies adaxial with phloem positioned abaxial. In a stem or root this means that the xylem is closer to the centre of the stem or root while the phloem is closer to the exterior. In a leaf, the adaxial surface of the leaf will usually be the upper side, with the abaxial surface the lower side. This is why aphids are typically found on the underside of a leaf rather than on the top, since the sugars manufactured by the plant are transported by the phloem, which is closer to the lower surface.
The position of vascular bundles relative to each other may vary considerably.
The vascular bundles are situated in a ring on the inside of the pericycle of the plant. This distinct ring of vascular bundles is a distinguishing characteristic of dicotyledonous stems. A mature vascular bundle consists of three main tissues - xylem, phloem and cambium. The phloem is located towards the outside of the bundle and the xylem towards the center. The cambium separates the xylem and phloem which bring about secondary thickening.
Functions of the Vascular Bundles
The xylem provides a passage for water and dissolved ions from the root system to the leaves.
The xylem also strengthens and supports the stem.
The phloem transports synthesized organic food from the leaves to other parts of the plant.
The cambium, divides to produce new xylem and phloem cells, making secondary thickening possible
The discontinuous vascular system of monocots (e.g., grasses) consists of scattered vascular bundles; the continuous vascular system of dicots (e.g., roses) surrounds the central pith.
Bundle-sheath cells are photosynthetic cells arranged into tightly packed sheaths around the veins of a leaf. They form a protective covering on leaf veins, and consist of one or more cell layers, usually parenchyma. Loosely arranged mesophyll cells lie between the bundle sheath and the leaf surface. The Calvin cycle is confined to the chloroplasts of these bundle sheath cells in C4 plants.
Xylem :
http://www.uic.edu/classes/bios/bios100/...
Thick secondary cell walls, often deposited unevenly in a coil-like pattern so that they may stretch
Dead at functionally maturity.
Involved in conduct of water and ions in the plant
Two types - tracheids and vessels
Tracheids - long, slender cells connected to each other by pits. Found in all vascular plants
http://www.uic.edu/classes/bios/bios100/...
Vessels - shorter, larger diameter cells with completely perforated cell wall ends. Found only in Angiosperms
http://www.uic.edu/classes/bios/bios100/...
Phloem :
http://www.uic.edu/classes/bios/bios100/labs/phloem.jpg
Involved in transport of sucrose, other organic compounds, and some ions
Living at functional maturity
Protoplast may lack organelles and nucleus, though
Endwalls connect to each other via sieve-plates
Two types of cells in the phloem - sieve-tube members and companion cells
Sieve-tube members - actual conduit for sucrose transport
Companion cells - has a nucleus that may also control the sieve-tube element and may aid in sucrose load
The xylem typically lies adaxial with phloem positioned abaxial. In a stem or root this means that the xylem is closer to the centre of the stem or root while the phloem is closer to the exterior. In a leaf, the adaxial surface of the leaf will usually be the upper side, with the abaxial surface the lower side. This is why aphids are typically found on the underside of a leaf rather than on the top, since the sugars manufactured by the plant are transported by the phloem, which is closer to the lower surface.
The position of vascular bundles relative to each other may vary considerably.
The vascular bundles are situated in a ring on the inside of the pericycle of the plant. This distinct ring of vascular bundles is a distinguishing characteristic of dicotyledonous stems. A mature vascular bundle consists of three main tissues - xylem, phloem and cambium. The phloem is located towards the outside of the bundle and the xylem towards the center. The cambium separates the xylem and phloem which bring about secondary thickening.
Functions of the Vascular Bundles
The xylem provides a passage for water and dissolved ions from the root system to the leaves.
The xylem also strengthens and supports the stem.
The phloem transports synthesized organic food from the leaves to other parts of the plant.
The cambium, divides to produce new xylem and phloem cells, making secondary thickening possible
The discontinuous vascular system of monocots (e.g., grasses) consists of scattered vascular bundles; the continuous vascular system of dicots (e.g., roses) surrounds the central pith.
Bundle-sheath cells are photosynthetic cells arranged into tightly packed sheaths around the veins of a leaf. They form a protective covering on leaf veins, and consist of one or more cell layers, usually parenchyma. Loosely arranged mesophyll cells lie between the bundle sheath and the leaf surface. The Calvin cycle is confined to the chloroplasts of these bundle sheath cells in C4 plants.
Xylem :
http://www.uic.edu/classes/bios/bios100/...
Thick secondary cell walls, often deposited unevenly in a coil-like pattern so that they may stretch
Dead at functionally maturity.
Involved in conduct of water and ions in the plant
Two types - tracheids and vessels
Tracheids - long, slender cells connected to each other by pits. Found in all vascular plants
http://www.uic.edu/classes/bios/bios100/...
Vessels - shorter, larger diameter cells with completely perforated cell wall ends. Found only in Angiosperms
http://www.uic.edu/classes/bios/bios100/...
Phloem :
http://www.uic.edu/classes/bios/bios100/labs/phloem.jpg
Involved in transport of sucrose, other organic compounds, and some ions
Living at functional maturity
Protoplast may lack organelles and nucleus, though
Endwalls connect to each other via sieve-plates
Two types of cells in the phloem - sieve-tube members and companion cells
Sieve-tube members - actual conduit for sucrose transport
Companion cells - has a nucleus that may also control the sieve-tube element and may aid in sucrose load
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