Botany Lecture 3
-
Upload
yousername -
Category
Documents
-
view
224 -
download
0
Transcript of Botany Lecture 3
-
8/12/2019 Botany Lecture 3
1/37
Spring Semester 2013
Botany
and Medicinal Plants
Department of PharmacognosyP ro f . Na h l a AyoubLec tu re 3 )
1
Pl nt cell
-
8/12/2019 Botany Lecture 3
2/37
Lecture Content
Pl nt cell I- Cell wall
1. Cellulose wall
2. Lignified wall
3. Suberinised &cutinised wall
4. Mucilagenous wall5. Chitinous wall
II-Different types of plant cells
1. Parenchymatous tissue
2. Collenchymatous tissue
3. Sclerenchyma (support cells)
Sclereids
Fibres
4. Vascular Tissue
Xylem Phloem
5. Secretory Tissue
secretory cell
Secretory cavities
Schizogenous
Lyzogenous
Schizo-
lyzogenous
Latex tissue
-
8/12/2019 Botany Lecture 3
3/37
Pl nt cell
I- Cell wall
-
8/12/2019 Botany Lecture 3
4/37
Cellulose, hemicellulose and pectin may be
present in the cell wall
Cellulose is the most abounded carbohydrates;
it form 50% or more of all the carbon in plants.
Detection
Cellulose+ iodine no bluecolor
Hemicellulose + iodine bluecolor
1. Cellulose wall
Cellulose: Polymer of glucose
(Plant fiber)
http://upload.wikimedia.org/wikipedia/commons/0/07/Cellulose_Sessel.svg -
8/12/2019 Botany Lecture 3
5/37
2. Lignified wall
Complex polymer ofphenolic compound
Cell wall of tracheids,vessels, fibers andsclereids
Lignified wall+phloroglucinol and HClgives red color
3. Suberinised &
cutinised cell wall
-Suberin& cutinare glycerolesters of some acids as suberic
acids.
-These material water proof
cells.
-Suberinis found in cork cell
and endodermal cell
-Cutincovers the epidermal cellof the leaves, which may show
papipllae, ridges and striation.
Cutin and suberin + suddan IIIred color
-
8/12/2019 Botany Lecture 3
6/37
1,6-hexanedicarboxylic acid
Subric acid (Covers the cork)
Cutin (Covers the
epidermal cells)
Papipllae
-
8/12/2019 Botany Lecture 3
7/37
4. Mucilagenous wall
5. Chitinous wall
-Cell wall is converted in some
cases intomucilage and gum
-Polysaccharide complexes ofsugar and uronic acid.
mucilage + Rhuthenium redred color
- Chitinforms the major part of
insect cell wall
-Chitin + 0.5% solution of iodinein potassium iodide then with
sulphuric acid.
violet color
-
8/12/2019 Botany Lecture 3
8/37
Pl nt cellII-Different types of plant
cells
-
8/12/2019 Botany Lecture 3
9/37
-
8/12/2019 Botany Lecture 3
10/37
Leaf Anatomy
http://www.nationmaster.com/encyclopedia/Image:Leaf-anatomy.svg -
8/12/2019 Botany Lecture 3
11/37
Leaf Anatomy
-
8/12/2019 Botany Lecture 3
12/37
vascular system
Stem Anatomy
-
8/12/2019 Botany Lecture 3
13/37
Dicot stems
Dicot stems have pith in the center, with vascular bundles forming a distinct ring. The outside ofthe stem is covered with an epidermis, which is covered by a waterproof cuticle. The epidermis
also may contain stomata for gas exchange. A cortex of parenchyma cells lies between theepidermis and vascular bundles.
-
8/12/2019 Botany Lecture 3
14/37
Vascular bundles are present throughout the monocot stem, although
concentrated towards the outside.
Monocot stems
-
8/12/2019 Botany Lecture 3
15/37
Root Anatomy
The Root Tip
Meristem- a region of
rapid mitosis, which
produces the new cells
for root growth.
Root cap- a sheath of
cells that protects the
meristem from abrasion
and damage as the
root tip grows through
the soil.
The Region of
Elongation
The cells produced by
mitosis undergo aperiod of elongation in
the direction of the axis
of the root. It is at this
time that they are
sensitive to gravity and
respond withgravitropism .
-
8/12/2019 Botany Lecture 3
16/37
1-Parenchymatous tissue
Occurrence: in various
parts of plant e.g. pith,cortex..& mesophyll of
the leaves.
Characters: isodiametric,
polygonal or rounded cell ,
cellulosic wall & may be
lignified and pitted
parenchyma
2-Collenchymatous tissue
Collenchyma is a living tissue
derived from parenchayma
with greater mechanical
strength showing thick wall
composed of cellulose.
Occurrence:the mechanical
tissue of the herbaceous stem
& of the petioles and the
midribs of the leaves
Characters: The cells are
usually 4 to 6 sided in
transverse section, axially
elongated in longitudinal
section
-
8/12/2019 Botany Lecture 3
17/37
1-Parenchymatous tissue
2-Collenchymatous tissue
Cellulosethickening
-
8/12/2019 Botany Lecture 3
18/37
3. Sclerenchyma (support cells)
Thick secondary cell walls (showing simple pitting)
Dead at functional maturity
Can not increase in length - occur in parts of the
plant which have quit growing in length
Two types: sclereids and fibres
-
8/12/2019 Botany Lecture 3
19/37
3. 1.Sclereids (Stone cells):
Occurrence: in hard outer coat of the
seeds, fruit, bark and the pericyclicregion (located between the endodermis
and phloem of the root).
Characters:isodimetric in shape. Thewall of the stone cells is thick,
lignified&may show well-marked
striation.
The cell lumens are small, sometimes
containing some diagnostic elements
e.g. prisms of calcium oxalate, or
starch granules.
-
8/12/2019 Botany Lecture 3
20/37
3.2. Fibers
Occurrence:in xylem, pericycle and phloem.
Characters:Spindle-shaped or elongated cells with
pointed ends known as prosenchyma.
The cell wall may be composed of cellulose or may
show some degree of lignifications.
Most mature fiber are unicellular.
-
8/12/2019 Botany Lecture 3
21/37
Fibers
-
8/12/2019 Botany Lecture 3
22/37
4-Vascular Tissue
There are two types ofvascular tissue: xylem
and phloem.
Vascular tissue may be
scattered in ground
tissue or regularly
arranged forming a
ring.
-
8/12/2019 Botany Lecture 3
23/37
Xylem conducts water from soil to leaves.
composed of sieveconducting tissuenutrient-Phloemtube or sieve cells mixed with parenchyma and fibers.
phloem transports organic molecules (particularlyThe
sugars) to wherever they are needed.
is the only part of a woody stem whereThe cambiumoccurs.cell division
It contains undifferentiated cells that divide rapidly toto the inside and secondaryxylemproduce secondaryto the outside.phloem
Vascular Tissue
-
8/12/2019 Botany Lecture 3
24/37
-
8/12/2019 Botany Lecture 3
25/37
A- Xylem
Xylemconducts waterfrom soil to leaves. The primary xylem is composed of protoand meta-
xylem.
Thickening occurs in the stem and root by formation
of secondary xylem.
The structural element of xylem are Xylem Tracheids: pitted elongated cells allow water to pass from one
to another
Xylem Vessels: the fundamental conducting elements of xylem
Xylem Parenchyma: storage tissue.
Xylem Fibers: Sclerenchyma fibers providing mechanical support to
the essential elements.
-
8/12/2019 Botany Lecture 3
26/37
Xylem Components (Tracheid, Vessels, Parenchyma and Fibers)
Tracheid
XylemVessel
Tracheid
Parenchyma
-
8/12/2019 Botany Lecture 3
27/37
Different Types of Xylem Vessels
Annular vessels :rings placed more or less at equal distance from each other.Spiral vessels : Helix or coil.Scalariform vessels : cross bands resembling the steps of a ladder.Reticulate vessels: irregular and appear in the form of a network.Pitted vessels : in which the secondary thickenings result in the formation of
depressions on the primary wall called pits.
Secondarythickenings
-
8/12/2019 Botany Lecture 3
28/37
sclariform
.Different Types of
Xylem Vessels:
annular
spiralreticulate
-
8/12/2019 Botany Lecture 3
29/37
Xylem Tracheid Xylem VesselXylem Tracheae
Xylem
parenchymacells
More primitive Pits allow water to
pass from one to
another
Less efficient at
conducting water
More like a fiber
Four typesannular, spiral,
reticulate and
sclariform.
Fundamentalconducting elements
of xylem.
Vessels are derived
from vertical series ofcells, dissolution of the
wall give continuous
tube.
Fourtypes of vessels.annular thickening of
the stem and root).
Spiral, sclariform
and reticulate.
Axiallyelongated,
sometimes thin
walled but often
with walls
showing
thickeninig and
lingification.
Xylem
parenchyma
function as
storage tissue.
-
8/12/2019 Botany Lecture 3
30/37
B- Phloem
Phloem is the food conducting tissue.
The phloem elements include sieve tubes, companioncelland phloem parenchyma
The sieve tubesformed from vertical series of
elongated cells interconnected by perforation in theirwalls in areas known as sieve plates.
The companion cellis intimately associated with
sieve tube structurally and functionally. Thecompanion cell is characterized by its dense protoplastand well developed nucleus and by thin cellulose wall.
The phloem may contain secretory cells
http://www.sbs.auckland.ac.nz/uoa/fms/default/science/about/departments/sbs/student_information/schools/nzplants/concepts/phloem_stern2(316).jpg -
8/12/2019 Botany Lecture 3
31/37
Phloem
http://www.sbs.auckland.ac.nz/uoa/fms/default/science/about/departments/sbs/student_information/schools/nzplants/concepts/phloem_stern2(316).jpghttp://www.sbs.auckland.ac.nz/uoa/fms/default/science/about/departments/sbs/student_information/schools/nzplants/concepts/phloem_stern2(316).jpg -
8/12/2019 Botany Lecture 3
32/37
Diagram showing the cross sections of a xylem and a phloem
-
8/12/2019 Botany Lecture 3
33/37
5. Secretory tissue
Secretorycavities
Schizogenous
Latex tissue
secretory cells
Lyzogenous
Schizo-lyzogenous
The vittae
Latex cells Latex vessels
-
8/12/2019 Botany Lecture 3
34/37
5. Secretory tissue Oil cells: occur in Cinnamon, Cassia and Ginger.
Secretory cavitiesor glands may be :
1. Schizogenous:arises by separation of cell andsubsequent formation of a secretory epithelium e.g.Eucalyptus.
2. Lyzogenous: formed by breakdown of the cell
forming a cavity not bounded by definite epitheliume.g. inGossypium.
3. Schizo-lyzogenouscavities occur in Rutaceae.
-
8/12/2019 Botany Lecture 3
35/37
Schizogenous Lysigenous Schizo-lysigenous
arises by separation of
cell and subsequent
formation of asecretory epithelium
formed by breakdown
of the cell forming a
cavity not bounded bydefinite epithelium
Initially schizogenous
but lysigeny occurs in
cavities in later stagesas the epithelium cells
lining the space
undergo autolysis
further enlarging thespace.
-
8/12/2019 Botany Lecture 3
36/37
Solid mass of
secreting cells
Formation of central cavity
By gradual disintegration of
cells starting from centre
Lyses of walls and
secretion
poured in the cavity
Lysigenous gland
Schizogenous gland
Epithelial cells secreteproducts in the cavity
Formation of central cavityBy separation of cells
-
8/12/2019 Botany Lecture 3
37/37
Latex tissue consist of latex cells or latex
vessels. Latex cells
Latex vessels: formed by partial or complete fusion of a
longitudinal series of cells.