2. Tissues
A group of closely associated cells that perform
related functions and are similar in structure.
3. Plant Tissues
❖ Tissues in plants that divide throughout their life.
❖ Plant tissues can be classified as:
❖ Growing or Meristematic tissue
❖ Permanent tissue
Meristematictissue
Permanent tissue
4. Meristematic Tissues
❖ The growth of plants occurs in certain specific
regions.
❖ This is because of the dividing tissue, known as
meristematic tissue
❖ Composed of actively dividing ceIIs, responsible for
the production of ceIIs.
❖ Capacity for division is restricted to certain parts of
the plant body called meristems
❖ Which are active throughout the life of the plant
body.
6. Kinds of meristems:
• 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. cork cambium
• Intercallary meristems – found at the bases of
young leaves & internodes
- responsible for further lengthening of
stems & leaves
Meristematic tissues
10. Simple permanent tissues
- consist only of one kind of cells
A. Dermal / Surface tissues
- external tissues
- 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 plant body
- covers the leaves, floral parts, fruits, seeds,
tems and roots
- generally only one layer thick with cuticle
- composed mostly of unspecialized cells, either
parenchyma and/or sclerenchyma
- contains trichomes, stomata, buIIiform ceIIs
(in grasses)
Dermal / Surface Tissues
13. Cuticle – Lines the outer waII of the epidermal ceIIs
- made up of waxy material that protects
plants from desiccation
Cuticle
Cuticle
Layer of
the leaf
14. • Stomata - pores for gas exchange
- present on one or both surfaces of Leaves.
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
Bulliform cells or motor cells are large,
bubble-shaped epidermal cells that occur
in groups on the upper surface of the
leaves of many monocots. During times of
stress, bulliform cells assist in the rolling of
leaves to avoid water loss through
transpiration.
17. • Periderm (Bark) is the outermost layer of stems and
roots of woody plants such as trees.
Dermal / Surface Tissues
19. 1. Parenchyma
- are the general purpose ceIIs of plants
- cells are rounded in shape & have uniformly thin
walls found in all parts of the plants.
- living at maturity, have large vacuoles
- location Ieaf, stem (pith), roots, fruits
Functions:
*basic metabolic function (respiration, photosynthesis
(chIorenchyma in leaf, & protein synthesis)
*storage (potatoes, fruits, & seeds)
*wound healing and regeneration
Types:
1. Chlorenchyma 3. Prosenchyma
2. Aerenchyma 4. Storage Parenchyma
Ground Tissues
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
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
25. 3. ScIerenchyma
❖ sclerenchyma cells which are non-living and lack
protoplasts at maturity
❖ Have thick, lignified secondary walls
❖ Provide strength and support in parts that have
ceased elongating or mature
Types:
1. Sclereids or stone cells
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!
29. Vascular Tissues
❖Specialized for long-distance transport of water
and dissolved substances.
❖Contain transfer ceIIs, fibers in addition to parenchyma
and conducting ceIIs.
❖Location, the veins in Ieaves
Types:
1. Xylem
2. phloem
Complex Permanent Tissues
30.
31. Xylem
❖GW xyIos w/c means “wood” transports water and
dissolved nutrients from the roots to aII parts of a plant.
❖ Direction of transport is upward.
There ate two types
• Primary xylem – differentiates from procambium in the
apical meristem & occurs throughout the primary plant
body.
• Secondary xylem – differentiates from vascular cambium
& is commonly called wood.
Xylem
33. • Xylary elements – the conducting cells in xylem
- 2 kinds of xylary elements:
tracheids – the only water conducting cells
in most woody, non flowering plants.
vessel elements – occur in several groups of
plants, including angiosperm.
- both are elongated, dead at maturity, lignified
secondary cell walls.
Xylem
Tracheids Vessel elements
34. PhIoem
- Greek word phloios meaning, “bark”
- transports dissolved organic / food materials from
the Ieaves to the different parts of the plant
- glucose in phloem moves in aII directions
Types
1. Primary phloem – differentiate from procambium
and
extends throughout the primary body of the plant.
2. Secondary phloem – differentiates from the
vascular cambium and constitute the inner layer
of the bark.
PhIoem
35. Sieve tube elements
❖main conducting ceIIs of phloem
❖elongated and non-nucleated
❖ uniformly thin walled with the end walls perforated to
from the sieve plate.
❖Sieve tube element are attached end to end to form
the sieve tube.
PhIoem
