لخّصلي

There are two types of root systems: {Tap Root System, Fibrous Root System, Primary Root, Secondary lateral Root, Adventitious Root}

1. Tap root System: o One main root with lateral branching root.o It produces secondary xylem inward and secondary phloem outward ?Casparian Strip: Endodermal cells with suberin"rich fat" on radial & transverse walls, #It blocks absorbed soil water from passing between the cells to the xylem; thus, water and mineral nutrients must pass through the selectively permeable membranes of endodermis cells instead, an effective filtering system. B)Vascular tissue system :{Pericycle, Xylem, Phloem} Pericycle: o Parenchyma "thin wall".o In secondary growth : epidermis & cortex replaced bark tissue "Cork &phelloderm".__________________________________________________ ?Root tissue:{ Non-Vascular Tissue Systems, VascularTissue System } A) Non-Vascular Tissue Systems: } Epidermis, Cortex } Epidermis : o Outermost tissue.Endodermis: The innermost layer of cortex, encircles Vascular tissue.o Adventitious Root: Root develop from stem, are initiated in parenchyma near differentiated Vascular tissue.o Carrot-like.?

There are two types of root systems:
{Tap Root System, Fibrous Root System, Primary Root, Secondary lateral Root,
Adventitious Root}

1. Tap root System:
   • One main root with lateral branching root.
   • Carrot-like.


2. Fibrous Root System :
   • Dense mass of multiple big roots with branches “grass like” .
   Primary Root :
   • From root of seedling.
   • Primary growth.
   • Epidermal cell wall become rubberized or cutinized with wax-like.
   Secondary lateral Root:
   • Originate from primary Root.
   • In secondary growth : epidermis & cortex replaced bark tissue
   “Cork &phelloderm”.


3. Adventitious Root:
   • From stem or leaves.
   • Prop roots of screw pine “pandanus”.

■Root tissue:{ Non-Vascular Tissue Systems, VascularTissue System }
A) Non-Vascular Tissue Systems: } Epidermis, Cortex }
Epidermis :
• Outermost tissue.
• Single layer.
• Root hair.
• Lateral protrusions.
• IN maturation zone.
• Active in water uptake.
Cortex :
Basically, cortex tissue is made up of parenchyma cells.
☆Monocots:
• without secondary growth.
• Cortex is retain.
-In conifers and dicots:
• with secondary growth.
• the cortex is shed.
♧ Endodermis:
The innermost layer of cortex, encircles Vascular tissue.
♧Casparian Strip: Endodermal cells with suberin“rich fat” on radial &
transverse walls,
#It blocks absorbed soil water from passing between the cells to the xylem;
thus, water and mineral nutrients must pass through the selectively permeable
membranes of endodermis cells instead, an effective filtering system.
B)Vascular tissue system :{Pericycle, Xylem, Phloem}
Pericycle:
• Parenchyma “thin wall”.
• Surround Vascular tissue.
• Pericycle, origin site of Vascular cambium & lateral root.
• Adventitious Root: Root develop from stem, are initiated in parenchyma
near differentiated Vascular tissue.
Xylem:
• If no xylem, parenchyma developethere.
• Primary xylem Arms radiate from center , vary number.
• In dicot: diarch“2 arms” , Triarch“3 arms” , Tetrarch “4 arms”.
• In monocot, polyarch“many arms”.
Phloem:
• Procambium cells, between the radiating arms of primary xylem.
• Produce primary phloem outward and xylem tissue inward.
• In secondary growth, the vascular cambiumaroundxylem arms and inside
the primary phloem poles.
• It produces secondary xylem inward and secondary phloem outward