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Anatomy
Organs
StemRoot
Leaves
1-Young dicot stem2- Monoct stem3- Old dicot stem
1 -young dicot root2 -monocot root3 -old dicot root
Identifying Stems and Roots Diagnostic:
Characteristic:
stemroot
pith and cortexsmall relative to pithpith small or absent
1 -V.B. are of radial type2 -xylem is always exarch ( protoxylem is located
near the periphery of the V.B(.3 -Absence of stomata and cuticle
Root anatomy Dermal tissue ( piliferous layer )One layer , no stomata , no cuticle , the outer wall may extend into root hair
Ground tissue
Cortex Parenchymatous ( dicot.) , some of them sclerenchyamtous (monocot.)Last layer of cortex termed as Endodermis which characterized by presence of casparian strips
{casparian strips : deposits of suberin and lignin on radial wall only Dicot.
On radial +inner tangential Monocot .
CharaterDicot. rootMonocot root
pericycleGive rise to lateral roots and
secondary meristems
Give rise to lateral root only
V.B.From 2-8Numerous , 20
CambiumAppear later as a secondary meristems
absent
PithSmall or absent Well developed
EndodermisCasparian strips
young dicot rootcortex Endodermis Metaxylem
protoxylem
phloem
pith
Starch
monocot rootcortex Endodermis Metaxylem
protoxylemphloem
pith
Starch epidermis
Old dicot. Root
Look at key board
old dicot root
Cork (phellem)Cork cambium (phellogen)Phelloderm2ry
phloemMedullary raysVascular cambium2ry
xylem
Organs
StemRoot
Leaves
1-Young dicot stem2- Monoct stem3- Old dicot stem
1 -young dicot root2 -monocot root3 -old dicot root
1 -dorsiventral dicot leaves2 -isobilateral dicot leaves
3 -monocot leaves
Leaf anatomy Epidermis Upper and lower surface , stomata on both sides
Ground tissue ( Mesophyll )
Specialized photosynthetic tissue In Dicot. Divided into
palisade Below epidermis and perpendicular to it , contain chloroplasts.
spongy tissue Loosely arranged , much less chloroplast than palisade.In Monocot.
Mesophyll cells all are alike not diffrantiated into palisade and spongy
Vascular tissue
Main V.B . In the center ( midrib ) , type of V.B . As the same of stem.
dorsiventral dicot leaves
EpidermisHybodermal layer
PalisadeSpongy tissueCollenchymaPericyclic fibersPhloemMetaxylemProtoxylem
EpidermisPalisadeSpongy tissue
isobilateral dicot leaves
Epidermis Palisade
Spongy tissueCollenchyma
Pericyclic fibersPhloemxylem
monocot leavesEpidermisHybodermal layer
(sclerenchyma (Ground tissue
(parenchyma(Bundle sheath
(fibers(PhloemMetaxylemProtoxylemClosed collateralV. B.
Practical work: We will do transverse section in a leaf:
tools razors
Slides and covers
Pith
