1. Meristem

8/3/2019 1. Meristem

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Tissue is a cellular

organizational level

intermediate

between cells and a

complete organism.

Tissues togethercarry out a specific

function.

Chapter 4. Tissue
http://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Cell_(biology)


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a) Apical Meristem: It is present at thegrowing tips of stems and roots and

increases the length of the stem and root.

4.2.1. Meristem

Classification of meristematic Tissue

b) Lateral Meristem: This meristemconsist of cells which mainly divide in oneplane and cause the organ to increase in

diameter and growth.

c) Intercalary Meristem: This meristemis located in between permanent tissues.It is usually present at the base of node,

inter node and on leaf base.

A meristem is the tissue in all plants consisting of undifferentiated cells(meristematic cells), found in zones of the plant where growth can take place.
http://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Biological_tissuehttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristem


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Shoot apical meristem (SAM)

Central zone (CZ)undifferentiated cells

Peripheral zone (PZ)formation of newlateral organsRib zone (RZ)formation of new stem

Layer 1 (L1)Generates

epidermisLayer 2 (L2)Layer 3 (L3)Generateinternal tissue

L1 + L2: anticlinal cell divisionsL3: randomly oriented cell divisions


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(a) Shoot apical meristem, (b) Leaf primordial,(c) Axillary bud primordium, (d) leaf, (e) Stem tissue


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Root apical meristem (RAM) - Root development

Root tip has four developmental zones:Root cap

Meristematic zoneElongation zoneMaturation (Differentiation) zone

RAM contains several types of stem cellsAll root tissues are derived from a small

number of stem cells in RAM


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Lateral meristem

It is a secondarymeristem whichoccupies lateralposition e.g.Cambium, Corkcambium (Conifer,Dicot). It is responsible

for increases in girth.


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http://www.uic.edu/classes/bios/bios100/labs/meristem.jpg


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Intercalary meristem ismeristem at the base of theinternode in monocot stems(particularly grass stems).

Only the apical meristem isactive. If the tip of the stem isremoved, the uppermostintact intercalary meristem

becomes the apical meristemand starts intercalary growth.

Intercalary meristem
http://www.puc.edu/Faculty/Gilbert_Muth/botglosm.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosi.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosm.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosa.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosi.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosi.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosa.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosa.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosm.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosi.htmhttp://www.puc.edu/Faculty/Gilbert_Muth/botglosm.htm


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It is the meristem that

occurs betweenpermanent tissues. Itrepresents the remnant of

the apical meristem. It isparticularly common atthe nodal regions. It mayalso occur at the base of

the leaves.


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SUMMARY


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a) Apical Meristem: It is present at the growing tips of stems and rootsand increases the length of the stem and root. They form growing parts atthe apices of roots and stems and are responsible for increase in length,also called primary growth. This meristem is responsible for the lineargrowth of an organ.

4.2.1. Meristem

b) Lateral Meristem: This meristem consist of cells which mainly dividein one plane and cause the organ to increase in diameter and growth.Lateral Meristem usually occurs beneath the bark of the tree in the formof Cork Cambium and in vascular bundles of dicots in the form of

vascular cambium. The activity of this cambium results in the formation ofsecondary growth.

c) Intercalary Meristem: This meristem is located in between permanenttissues. It is usually present at the base of node, inter node and on leafbase. They are responsible for growth in length of the plant. This adds

growth in the girth of stem.

Classification of meristematic Tissue
http://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Vascular_cambiumhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Vascular_cambiumhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristemhttp://en.wikipedia.org/wiki/Meristem


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Ground tissue: Ground tissue is less differentiated than

other tissues. Ground tissue manufactures nutrients by

photosynthesis and stores reserve nutrients.

Epidermis: Cells forming the

outer surface of the leaves

and of the young plant body.

Vascular tissue: The primarycomponents of vascular

tissue are the xylem and

phloem. These transport fluid

and nutrients internally.

Classification of Tissue
http://en.wikipedia.org/wiki/Ground_tissuehttp://en.wikipedia.org/wiki/Epidermis_(botany)http://en.wikipedia.org/wiki/Vascular_tissuehttp://en.wikipedia.org/wiki/Vascular_tissuehttp://en.wikipedia.org/wiki/Epidermis_(botany)http://en.wikipedia.org/wiki/Ground_tissue

1. Meristem

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