It produces cork cambium and interfascicular cambium. Protoderm It gives rise to epidermal tissue system and develops into epidermis,stomata and hairs. Procambium It gives rise to primary vascular tissues. Example: xylem and phloem .
Ground Meristem It gives rise to all tissues except epidermis and vascular strands. Mass meristem It divides in all planes. Example: endosperm,young embryo and sporangium Rib meristem or File meristem It divides anticlinally in one plane. Example: development of cortex and pith Plate meristem It divides anticlinally in two planes.
Example: development of epidermis . The corpus : It is the inner zone of shoot apex,that forms cortex and stele of shoot. Root Apical Meristem Root apex is present opposite to the shoot apex. The roots contain root cap at their apices and the apical meristem is present below the root cap.
The different theories proposed to explain root apical meristem organization are given below. Apical Cell Theory Apical cell theory is proposed by Nageli. The single apical cell or apical initial composes the root meristem. The apical initial is tetrahedral in shape and produces root cap from one side.
The remaining three sides produce epidermis, cortex and vascular tissues. It is found in vascular cryptogams. Histogen Theory Histogen theory is proposed by Hanstein ( ) and supported by Strassburgur . The histogen theory as appilied to the root apical meristem speaks of four histogen in the meristem.
They are respectively, This apical cell governs the growth and development of whole plant body. It is applicable in Algae, Bryophytes and in some Pteridophytes. Histogen Theory Histogen theory is proposed by Hanstein ( ) and supported by Strassburgur. The shoot apex comprises three distinct zones.
. Dermatogen: It is the outermost layer. It gives rise to epidermis. .
Periblem: It is middle layer. That gives rise to cortex. . Plerome: It is innermost layer.
Which gives rise to stele Tunica Corpus Theory Tunica corpus theory is proposed by A. Schmidt ( ). Two zones of tissues are found in apical meris tem. .
The tunica : It is the peripheral zone of shoot apex,