Plant Tissues.pdf

Plant Tissues

2. Tissues
A group of closely associated cells that perform
related functions and are similar instructure.

3. PlantTissues
❖Tissues in plants that divide throughout theirlife.
❖Plant tissues can be classifiedas:
❖Growing or Meristematic tissue
❖Permanenttissue
Meristematictissue
Permanenttissue

4. MeristematicTissues
❖The growth of plants occurs in certain specific
regions.
❖This is because of the dividingtissue, known as
meristematictissue
❖Composed of actively dividing ceIIs, responsible for
the production ofceIIs.
❖Capacity for division is restricted to certain partsof
the plant body calledmeristems
❖Which are active throughout the life of the plant
body.

5. MeristematicTissues

6. Kinds ofmeristems:
• Apical meristems –found at the tip of stems &
roots
• Lateral meristems –a.k.a.cambia
-found along the sides of roots &stems
-increase width or diameter of stems &roots
-types: 1. vascular cambium 2. corkcambium
• Intercallary meristems –found at the bases of
young leaves &internodes
-responsible for further lengtheningof
stems &leaves
Meristematictissues

7. Meristematictissues

8. PermanentTissues
❖Tissues that attained their mature form and
perform pacificfunctions.
❖They stopdividing
Types:
•Simple permanenttissues
•Complex permanenttissues

9. PermanentTissues
SIMPLE COMPLEX

10. Simple permanenttissues
-consist only of one kind ofcells
A. Dermal / Surfacetissues
-externaltissues
-forms protective covering of the plant body
a.Epidermis
b.Periderm
B. Ground tissues
-all the other tissue in a plant that isn't dermal
tissue or vascular tissue
a. Parenchyma c. Sclerenchyma
b. Collenchyma
Simple Permanent Tissue

11. •Epidermis
-the outermost layer of the primary plantbody
-covers the leaves, floral parts, fruits,seeds,
tems androots
-generally only one layer thick withcuticle
-composed mostly of unspecialized cells,either
parenchyma and/orsclerenchyma
-contains trichomes, stomata, buIIiformceIIs
(ingrasses)
Dermal / Surface Tissues

12. Structure ofepidermis

13. Cuticle –Lines the outer waII of the epidermalceIIs
-madeupof waxymaterialthatprotects
plants fromdesiccation
Cuticle
Cuticle
Layerof
theleaf

14. •Stomata -pores for gasexchange
-present on one or both surfaces ofLeaves.
Stomata

15. Trichomes
Trichomes – outgrowths of epidermal cells.
Trichomes play an important role in
plant growth and development by
protecting them from UV light, insect
predation, and excess transpiration.

16. Bulliform cells
Bulliformcellsormotorcellsarelarge,
bubble-shapedepidermalcellsthatoccur
ingroupsontheuppersurfaceofthe
leavesofmanymonocots.Duringtimesof
stress,bulliformcellsassistintherollingof
leavestoavoidwaterlossthrough
transpiration.

17. •Periderm (Bark) is the outermost layer of stems and
roots of woody plants such astrees.
Dermal / Surface Tissues

18. GroundTissues

19. 1.Parenchyma
-are the general purpose ceIIs ofplants
-cells are rounded in shape & have uniformlythin
walls found in all parts of theplants.
-living at maturity, have largevacuoles
-location Ieaf, stem (pith), roots,fruits
Functions:
*basic metabolic function (respiration,photosynthesis
(chIorenchyma in leaf,& proteinsynthesis)
*storage (potatoes, fruits, &seeds)
*wound healing andregeneration
Types:
1. Chlorenchyma 3. Prosenchyma
2. Aerenchyma 4. Storage Parenchyma
GroundTissues

20. Parenchyma
•Loosely packed, cube-
shaped or elongated cells
with large central
vacuoles
•Involved with many
metabolic functions
including photosynthesis
•Usually form the bulk of
nonwoody plants
•Alive at maturity

21. Parenchyma

22. 2.Collenchyma
❖a supporting tissue characteristic of the growing
organs of many herbaceous and woody plants
❖Have irregularly thick cell walls, made up of cellulose
and pectin
❖Provide plants elasticity and rigidity
Collenchyma

23. Collenchyma
•Thicker cell walls
•Provide support for the
plant
•Usually in founds in
strands
•Celery has a lot of
collenchyma cells
•Alive at maturity

24. Collenchyma

25. 3.ScIerenchyma
❖sclerenchyma cells which are non-living and lack
protoplasts atmaturity
❖Have thick, lignified secondarywalls
❖Provide strength and support in parts that have
ceased elongating ormature
Types:
1. Sclereidsor stonecells
2.Fibers
ScIerenchyma

26. Sclerenchyma
•Thick,even,rigid cell walls
•Support and strengthen in
areas of plant no longer
growing
•Dead at maturity
•This is FIBER!
The gritty texture of the pear fruit is due to sclerenchyma cells!

27. Sclerenchyma

28. GroundTissues

29. VascularTissues
❖Specialized for long-distance transport of water
and dissolvedsubstances.
❖Contain transfer ceIIs, fibers in addition to parenchyma
and conductingceIIs.
❖Location, the veins inIeaves
Types:
1.Xylem
2.phloem
Complex PermanentTissues

31. Xylem
❖GW xyIos w/c means “wood” transports water and
dissolved nutrients from the roots to aII parts of aplant.
❖Direction of transport is upward.
There ate twotypes
•Primary xylem –differentiates from procambium in the
apical meristem & occurs throughout the primary plant
body.
•Secondary xylem –differentiates from vascular cambium
& is commonly calledwood.
Xylem

32. Xylem

33. •Xylary elements –the conducting cells inxylem
-2 kinds of xylaryelements:
tracheids –the only water conductingcells
in most woody, non floweringplants.
vessel elements –occur in several groups of
plants, includingangiosperm.
-both are elongated, dead at maturity,lignified
secondary cellwalls.
Xylem
Tracheids Vesselelements

34. PhIoem
-Greek word phloios meaning,“bark”
-transports dissolved organic / food materialsfrom
the Ieaves to the different parts of theplant
-glucose in phloem moves in aIIdirections
Types
1. Primary phloem –differentiate from procambium
and
extends throughout the primary body of theplant.
2. Secondary phloem –differentiates from the
vascular cambium and constitute the inner layer
of thebark.
PhIoem

35. Sieve tubeelements
❖main conducting ceIIs ofphloem
❖elongated andnon-nucleated
❖uniformlythinwalledwiththeendwallsperforatedto
from the sieveplate.
❖Sievetubeelementareattachedendtoendtoform
the sievetube.
PhIoem

36. PhIoem