4. MERISTEMIC TISSUES
Small
Living tissues
Unspecialised
Dividing - Mitosis
Large nuclei, Dense cytoplasm with small vacuoles
Become specialized when matured
Embryonic meristem do not stop dividing throughout
the entire lifespan
Only found in certain areas
5. TYPES OF MERISTEMIC TISSUES
• Root tips
• Shoot tips
Apical • Primary growth – increase length
• At nodes
• Monocots
Intercalary • Grow quicker after being cut
• Also called cambium
• Secondary growth – increase diameter
• Vascular cambium – secondary xylem & phloem
Lateral • Cork cambium – For outer cork layer + suberin – Reduce evaporation
6.
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14. GROUND TISSUES
PARENCHYMA CELLS
Living tissue
Contain
cellulose, hemicellulose, pectin
Secondary cell wall absent
Permeable to water and solutes
Large vacuoles, Thin cytoplasm
Food storage - Apple
Water reserve
Support & Shape for Herbaceous
plants
Large air space for Photosynthesis
Palisade mesophyll
Sponge mesophyll
16. UNSPECIALISED PARENCHYMA
GROUND TISSUE
Fruits, Roots, Stem, Leaves
In herbaceous plants
Spherical & Thin-walled
Large vacuole
Thin primary wall, without
secondary walls
Turgid cells
Provide support
17. SPECIALISED PARENCHYMA CELLS
Epidermis Mesophyll cells
Elongated and flattened
Palisade mesophyll
Secrete cutin - Waxy
cuticle Compact cells with
Protective barrier chloroplast
Water loss Spongy mesophyll
Bacteria
Loose cells with fewer
chloroplast
Form stomata
Gaseous exchange
Transparent layer
18. SPECIALISED PARENCHYMA CELLS
Endodermis
Selective barrier Between outer cortex and inner
pericycle
Forming Casparian strip in the roots to prevent
apoplastic movement of water (suberin)
Pericycle
Secondary growth of roots
Aerenchyma
Oxygen reserve
Buoyancy for Hydrophytes
24. TYPES OF
SCLERENCHYMA
Fibers – are long thin
and fibrous like and
usually occur in bundles
commercially used to
make rope and flax fibers
Found together with
xylem
Sclereids – short and
irregular in shape.
make up tough seed
coats and pits
give pears its gritty texture
28. XYLEM
Transport water and minerals
Types of Cells
Tracheids
Vessel elements
Xylem fibres (sclerenchyma)
Die on maturity
Xylem parenchyma Cytoplasm disintegrate
Empty cavity
Lignified – Do not collapse
Have pits – Allow lateral movement
of water
29. XYLEM
Tracheids Vessel elements
Longer Shorter
Smaller diameter Larger diameter
Tapered at 2 ends to Joined end to end
increase strength Hollow tube
Have pits in between No pits in between
More resistance Have pits side-by-side with
tracheids
Lignified
Less resistance for water
No perforated open ends Strengtened with lignin
between cells
Absent in fern and conifers
Not hollow tube
32. VESSEL ELEMENTS Spiral / Annular thickening
High rate of elongation
Present in young plants to allow
stretching during elongation
Present in proxylem
Scalariform / Reticulate /
Pitted thickening
Low rate of thickening
Cannot be stretched
More lignifications
High tensile strength
Do not collapse when water flow
through in high tension
Have pits for lateral movements
of water
34. XYLEM FIBRES & PARENCHYMA
Xylem fibers – similar to
sclerenchyma fibers
Dead and lignified
Only for support
Parenchyma – Living cells
As intermedularry rays for radial
transport of food, water, gases
and storage
35. PHLOEM
Translocation of organic substances
Four types of cells
Sieve tube cells
Companion cells
Phloem parenchyma
Pholem fibres
39. CONTINUOUS CYTOPLASM
Sieve tube elements
Alive with thin cell wall and
protoplasm
Upon maturity, nucleus,
ribosome and Golgi
apparatus disintegrates
Only have mitochondria and
ER left for periphery transport
40. COMPANION CELL
Only found in angiosperms
Parenchyma cell
Elongated
Thin primary wall
Metabolically active
Dense cytoplasm
Large nucleus
Mitocondria
Plastids
Vacuoles
RER
Linked to sieve tube
elements by Plasmodesmata
41.
42. PHLOEM PARENCHYMA & FIBRES
Parenchyma
Food storage
Form radial
medullary rays
in phloem
Fibres
Support