Clasification of meristem .apical meristem

Clasification of meristem .apical meristem

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  Classification of Meristems:Apical Meristems Presentedby :Prajapati Dimple B. M.sc sem -2 Roll no -212 Department of Life sciences , H.N.G.U.,Patan
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  Content • What isMeristem? • Classification of Meristem • Apical Meristem
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  What is Meristem? •A region of plant tissue , found chiefly at the growing tips of roots and shoots and the cambium consisting of actively dividing cells forming new tissue. • A meristematic tissue consists of a group of cells which remain in continuous state of division or they retain their power of division.
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  Classification of Meristems •Meristem Based on stage Development • Meristems Based on origin of Initilating • Meristems Based on position in plant Body 1. Apical Meristem 2. Intercalary Meristem 3. Lateral Meristem • Meristems Based on function
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  Meristems Based onstage Develpoment • Promeristem or Primordial meristem: 1. Promeristem is the region of new growth in a plant body where the foundation of new organs or parts of oragans is initiated . 2. Sometimes it is also called primordial meristem , urmeristem and embryonic meristem.
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  Meristems Based onorigin of Initilating cells 1. Primary meristem 2. Secondary meristem • Primary meristems: 1. The primary meristems are those that build up primary part of the plant and consist in parts of promeristem. 2. In primary meristem,promeristem is always the earliest stage. 3. The possession of promeristem continuously from an early embryonic origin is characteristic of primary meristem. 4. The main primary stems are the apices of roots,stems and leaves ,similar appendages.
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  • Secondary meristems: 1. The secondary meristems appears later at a stage of development of an organ of a plant body. 2. The seconary meristems always arise in permanent tissue and they are always found lying lateral along the of stem and root. 3. Sometimes some of the primary permanent tissues actually the power of division and become meristematic. 4. The secondary meristems are so called because they arise as new meristems in tissue which is not meristematic. 5. The most striking example of secondary meristem is phell or cork cambium.
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  Meristems Based onPosition in Plant Body
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  Meristems Based onfunction • As regards their function a systems of classification of meristems was proposed by Haberlandt in the end of 19th century. • He suggested that the primary meristem at the apex of the stem and root is distinguished into three tissues – protoderm,procambium and ground or fundamental meristem. • The protoderm is the outermost tissue which develops into epidermis. • The procambium develops into primary vascular tissues. • The ground or fundamental medistem develops into ground tissue and pith. • They become differentiated into hypodemis, cortex, endodermis,pericycle,pith, rays and pith.
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  Apical Meristem • Theapical meristem includes the meristematic initials and their immediate derivatives at the apex of a shoot or root. • The apical meristem thus delimited corresponds approximately to the promeristem,and to cotrast with the partly develpoment derivatives of the promeristem,i.e.,the protoderm ,the ground meristem and the procambium.
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  1. They arecomposed of immature cells which are in a state of division and growth. 2. Usually the intercellular spaces are not found among the cells. 3. The cells may be rounded , oval or polygonal in shape they are always living and thin walled. 4. Each cell of meristematic tissue possesses abundant cytoplasm and one or more nuclei in it. 5. The vacuoles in the cells may be quite small or altogether absent.
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  Reference • A TextBook of Botany Angiosperms by B.P. Pandey • https://en.m.Wikipedia.org • https://www.slideshare.net • www.biologydiscussion.com
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