1. UNIT 5: PLANT TISSUE

2. PLANT BODY ORGANS Plants have organs that compose of different tissue,
which in turn are composed of cells of different types.
A tissue is a group of cells with a common function, structure or both.
An organ consist of several types of tissues that together carry out particular functions.

3. The three basis plant organs are: Roots, stems leaves.
The organs are divided into
the root system (roots and mycorhiza)
shoot system (leaves and stems)
SHOOT SYSTEM
ROOT SYSTEM

4. ROOTS Anchor plants Root hairs absorb water and minerals.
Stores carbohydrates.
Eudicots have a taproot system (one main vertical root that give rise to lateral roots)
Monocots have an adventitious root system (roots that originate from the stem of a plant)

5. Roots can be modified to perform different functions:
Fig. 35-4
Roots can be modified to perform different functions:
Prop roots
Many plants have modified roots
“Strangling”
aerial roots
Storage roots
Buttress roots
Pneumatophores

6. STEMS Consist of nodes (where leaves grow) and internodes.
The angle between the leave and the stem is called the axillary bud, this can form a lateral shoot.
The shoot tip consist of an apical (end) bud.
The inhibition of axillary buds by an apical bud is called apical dominance.
Stems support the leaves and lateral branches of a plant.
Stems keep the plant upright.

7. Many plants have modified stems
Fig. 35-5
Rhizomes
Bulbs
Storage leaves
Many plants have modified stems
Stem
Stolon
Tubers

8. Rhizome: Horizontal shoot that grows just below the surface
Rhizome: Horizontal shoot that grows just below the surface.Vertical shoots emerge from auxillary buds on the rhizome.
Stolon: Horizontal shoots that grow along the surface. Reproduce asexually.
Tubers: Enlarged ends of rhizome or stolon, specialized to store food. The eyes are clusters of auxillary buds that mark the nodes.

9. LEAVES
Main photosynthetic part of the plant (in most vascular plants).
Consist of a flattened blade and a stalk, called a petiole.
Monocots have no petiole.
Monocots have parallel veins on the leaves and Eudicots have net venation.
Leaf shape differs: simple leaves (single leaf) and compound leaves (where the blade consist of smaller leaflets – leaflets have no axillary buds.)

10. DIFFERENT LEAF STRUCTURES
Fig. 35-6
(a) Simple leaf
DIFFERENT LEAF STRUCTURES
Petiole
Axillary bud
Leaflet
(b)
Compound
leaf
Petiole
Axillary bud
(c)
Doubly
compound
leaf
Leaflet
Petiole
Axillary bud

11. Tendrils Spines Storage leaves Reproductive leaves Bracts
Fig. 35-7
Tendrils
Some plant species have evolved modified leaves that serve various functions
Spines
Storage
leaves
Reproductive leaves
Bracts

12. Tissue categories in plants
Each plant organ has:
dermal,
vascular and
ground tissues.
Each of these three categories forms a tissue system.
The dermal tissue system is the plant’s outer protective covering.
In non-woody plants it is a single layer called the epidermis protected by a waxy layer called the cuticle found on stems and leaves.
In woody plants, the protective tissue is called periderm.

13. Ground tissue are neither dermal or vascular.
Internal ground tissue is called the pith.
Ground tissue that is external to the vascular tissue is called cortex.
Ground tissue includes various cells with specialized functions such as storage, photosynthesis and supports.

14. MERISTEMATIC TISSUE
A flowering plant has the ability to grow its entire life because it possesses meristematic (embryonic) tissue.
The apical meristem are located at or near the tips of stems and roots, where they increase the length of their structures by means of mitosis.
This increase in length is called primary growth.
Monocots also have an intercalary meristem, this allows them to regrow lost parts. (It is found between mature tissues). EXAMPLE: GRASS CUT - GROW

15. Organization of a plant body
MERISTEMATIC TISSUE AT TIP OF STEM
MERISTEMATIC TISSUE AT TIP OF ROOTS

16. SPECIALIZED PRIMARY TISSUES:
APICAL MERISTEM
Produces three types of meristems, and these develop into the three types of specialized primary tissues in the body of the plant:
SPECIALIZED PRIMARY TISSUES: 
Protoderm gives rise to the epidermis
Ground meristem produced ground tissue
Procambium produces vascular tissue

17. FUNCTIONS OF SPECIALIZED TISSUES
Epidermal tissue: forms the outer protective covering of a plant.
Ground tissue fills the interior of a plant.
Vascular tissue transports water and nutrients in a plant and provides support.

18. EPIDERMAL TISSUE

19. EPIDERMAL TISSUE
Single layer of closely packed, flat, brick shaped cells, with a large vacuole.
The aerial parts of the plant are covered with a cuticle.
Functions:
- Cuticle minimizes water loss (because it has cutin)
- Protects the plant against bacteria.
Longitudinal section
Cross section

20. Leaf contain upper and lower epidermal cells

21. SPECIALIZE EPIDERMAL CELLS
TRICHOMES
ROOT HAIR
TRICHOMES
STOMA OF LEAF
CORK OF OLDER STEMS
ROOT HAIRS
STOMATA
CORK CELLS

22. ROOT HAIRS They are specialized epidermal cells of roots.
Unicellular outgrowth of the epidermal cell.
Functions:
Increase the surface area of the root for absorption of water and minerals.
Anchor the plant.

23. TRICHOMES Specialized epidermal cell of stems and leaves.
Multicellular outgrowths of the epidermis of stems and leaves.
Functions:
Protect the plant from sun
Conserve moisture.
Protect plant from herbivores, produce toxic substance.
CUTICLE
MULTICELLULAR

24. STOMATA
Specialized epidermal cells called guard cells, which are bean shaped, enclose an opening called the stoma or pore.
The guard cells contain a nucleus and chloroplasts.
It has a thick inner membrane and a thin outer membrane.
Woody plants have lenticels.
FUNCTIONS:
Transpiration
Gaseous exchange take place through the stomata.

25. CLOSED- NIGHT
OPEN - DAY

26. PARENCHYMA COLLENCHYMA SCLERENCHYMA
GROUND TISSUE
PARENCHYMA
COLLENCHYMA
SCLERENCHYMA

27. GROUND TISSUES

28. PARENCHYMA TISSUE FUNCTIONS: Occur in roots, stems and leaves.
If they have chloroplasts – photosynthesis.
If they have leucoplasts – they store products of photosynthesis.
They can divide to form more specialized cells
Occur in roots, stems and leaves.
Spherical, loosely packed, big, thin-walled cells with large vacuoles.
Intercellular airspaces between cells.

29. INTERCELLULAR AIR SPACES
PARENCHYMA CELLS

30. COLLENCHYMA TISSUE FUNCTIONS:
Mechanical strengthening and support to plant organs
It is composed of unevenly thickened primary walls with additional cellulose and pectin deposits especially in the corners.
Found just beneath the epidermis of young stems.
The cells are slightly elongated, tightly packed and overlap each other.

32. SCLERENCHYMA TISSUE
Cell walls have been thickened by impregnation with lignin.
The cell wall is evenly thickened and forms a waterproof barrier impermeable to water.
In the cell walls are pit canals that serve as channels between cells and to the outside world.
The lumen is small.
Two types of Sclerenchyma:
Stone cells and fibers
FUNCTIONS:
Strengthening, support and protection.
Found in shell of nuts and hard parts of fruits
Fibers give rigidity and flexibility to the plant.

34. Vascular tissue
XYLEM
PHLOEM

35. XYLEM
Contains 2 types of conducting cells: tracheids and vessel elements (VE).
Both cells are hollow and non-living but the VE is larger and has perforated plates in their end walls and are arranged to form a continuous vessel.
Tracheids have tapered ends with pits.
It also has other tissue: Xylem fibers, and Xylem parenchyma.

36. FUNCTIONS OF XYLEM
Transports water and minerals from the roots to the leaves.
Support and strengthening.
Xylem vessels
Xylem tracheids Xylem fibers

37. PHLOEM Consist of sieve-tubes and companion cells.
The sieve-tubes form a continuous tube, they have cytoplasm but no nuclei.
They have sieve plates between cells.
The companion cell has a nucleus that controls both cells because they are connected by plasmodesmata.
It also has other tissue: Phloem fibers and phloem parenchyma

38. FUNCTIONS OF PHLOEM
Transports sucrose and other organic substances, including hormones, from the leaves to the roots.
Support and strengthening.

39. Tissue organization of Leaves
KNOW CROSS SECTION THROUGH LEAF