1. Plant Tissues
Tissue – group of vegetative cells with one or more specific functions.
Two kinds based on state of development:
Meristematic tissues or Meristems
Actively engaged in cell division (production of new cells)
Enlarge and differentiate to become permanent tissues
Remain meristematic or repeatedly divide (initials)
Permanent tissues
Attained mature form and perform their specific functions
No longer divide and give rise to new cells
All are derived from meristematic tissues

2. Kinds of Meristems
Based on position or location within the plant body:
Apical meristems (promeristems)
Found at the tips or apices of stems and roots
Responsible for the increase in length of stems and roots
3 meristematic zones:
Protoderm, Ground meristem, Procambium
Lateral meristems (or cambia)
Found along the sides of certain roots and stems
Responsible for the increase in width or diameter
Dicots have cambia whereas monocots have no cambia
Types: vascular cambium and cork cambium (phellogen)
Intercalary meristems
Found at the bases of young leaves and internodes
Considered temporary (short-lived) meristems

3. Kinds of Meristems Based on origin, meristems may be classified as:
Primary meristems
Originate in the embryo and persist throughout the lifetime
Apical meristems or their meristematic zones
Intercalary and the vascular cambium
Secondary meristems
Derived from permanent tissues
Cork cambium
Living permanent tissues lining injured or wounded portions of plants become meristematic to heal the injured portions resulting in formation of “callus” or scar tissue.

4. Kinds of Permanent Tissues
Based on the number of cell types/kinds of cells:
Simple permanent tissues
for the most part consist of only one kind of cell
Composed of similar in structure and function
Complex permanent tissues
Consist of several kinds of cells working together as a unit in carrying out one or more specific functions

5. Different Kinds of Simple Permanent Tissues
Epidermis
External tissue consists of single layer of living cells
Serves as outermost tissue of leaves, young roots and young stems; also in old roots and old stems of monocot plants and herbaceous dicot plants
Appear cubical or rectangular in shape
In terms of function, a protective tissue
In leaves and stems:
2 kinds of cells:
Ordinary epidermal cells
Guard cells (kidney-shaped) which occur in pairs and bound by tiny openings or pores called stomata

6. epidermis
cortex
vascular bundle
pith

7. Different Kinds of Simple Permanent Tissues
Epidermis
In leaves and stems:
2 kinds of cells:
Ordinary epidermal cells
Guard cells (kidney-shaped) which occur in pairs and bound by tiny openings or pores called stomata.
Outer wall is coated with a heavy waxy substance (cutin or cuticle) that prevents excessive transpiration or evaporation of water from the leaves and stems; roots not cutinized
Epidermal hairs (trichomes) for protective function

8. Different Kinds of Simple Permanent Tissues
Parenchyma
Internal tissue
Consists of living cells with uniformly thin cell walls
Large intercellular spaces
In cross section, appear rounded
Chlorenchyma – parenchyma with chloroplastids
Involved in food manufacturing and in food storage

9. Parenchyma Cells
- Parenchyma cells are living cells with uniformly thin walls. They comprise the photosynthetic tissue of a leaf, the soft flesh of fruits, and the storage tissue of roots and seeds.
- A widely distributed tissue located beneath the collenchyma between the vascular bundles (consisting of vascular tissues and at the center of the section.
epidermis
collenchyma
parenchyma

10. Different Kinds of Simple Permanent Tissues
Collenchyma
Also an internal tissue
Consists of living cells with unevenly thickened walls– thin on the sides but thickened at the angles where two or more cells meet
Appear cubical or slightly rectangular and are more or less compactly arranged
A strengthening or support tissue; storage of food

11. Collenchyma Cells
Collenchyma cells have unevenly thickened cell walls, which are their distinguishing characteristic. They form strands along veins in leaves and beneath the epidermis in stems to provide support and strength against the onslaught of strong winds and rains.

12. Different Kinds of Simple Permanent Tissues
Sclerenchyma
Also an internal tissue
Consists of dead cells when mature, with heavily thickened cell walls mainly due to the deposition of lignin
It may appear in the form of fibers or sclerids
Fibers –elongated cells with tapering ends occurring in groups; appear as cells with tiny empty cell cavities or cell lumina with heavy and uniformly thickened cell walls in cross section
Sclerids –irregularly-shaped cells and typically not elongated; various forms but the most common are stone cells (isodiametric and like sand particles occur singly or in groups)
Found in fruits: coconut shell is sclerids, coconut husk is fibers
gritty texture of sugar apple (atis) and chico due to stone cells
Strengthening or supportive tissue

13. Sclerenchyma Cells
- Sclerenchyma cells have thick and rigid cell walls. They serve as strengthening elements to support mature plant parts.
- Found in groups of cluster among the parenchyma cells around the vascular tissues

14. Different Kinds of Simple Permanent Tissues
Cork
External tissue serving as outermost tissue or covering of old stems/roots of woody dicot plants
Consists of several layers of dead cells when mature
Cell walls are impregnated with waxy substance (suberin) – impermeable to substances, resulting to the death of cells upon reaching maturity
Rectangular in shape and arranged in layers in cross-section
Protective tissue

15. BARK periderm epidermis phellem (cork) phellogen (cork cambium)
phelloderm
cortical parenchyma
phellem
periderm
phellogen
phelloderm

16. Plant Cell Types PLANT CELL TYPE PROTOPLASM +/-, CELL LIVING OR DEAD
CELL WALL CHARACTERS
FUNCTION
CELL THICKNESS
CHEMICAL COMPOSITION
Parenchyma
+, living
Uniformly thin
Cellulose, hemicellulose
may have cutin
Food storage, food manufacture
Collenchyma
Irregularly thick
Food storage, strengthening
Sclerenchyma
1. sclereid
2. fiber
-, dead
Uniformly thick
Cellulose, hemicellulose added suberin or lignin
Strengthening
and support
CELL SHAPE
Polyhedral to much branched sclerenchyma cells
Long and slender sclerenchyma cells

17. Kinds of Complex Permanent Tissues
Phloem
Function: mainly conductive or vascular tissue
Conducts dissolved organic food materials
Consists of the following cell types:
Phloem fibers
Phloem parenchyma
Sieve tube elements
Companion cells

18. Kinds of Complex Permanent Tissues
Phloem: cell types
Phloem fibers
appear like ordinary schlerenchyma fibers
Phloem parenchyma
appear like ordinary parenchyma cells

19. Kinds of Complex Permanent Tissues
Phloem: cell types
Sieve tube elements
conducting cells of the phloem
living, non-nucleated cell when mature
elongated in form and uniformly thin-walled with the end walls perforated to form sieve plates that are attached end-to-end forming long conducting tubes (sieve tubes)
consists of protoplasmic connections between adjacent cells - plasmodesmata

20. Kinds of Complex Permanent Tissues
Phloem: cell types
Companion cells
parenchymatous cells which are always found beside the sieve tubes
small, elongated and nucleated living cells when mature
plasmodesmata have also been observed to occur between the companion cells and the sieve tubes

21. Kinds of Complex Permanent Tissues
Xylem or Wood
Function: mainly conductive or vascular tissue
Conducts water and mineral salts
The main strengthening tissue of the plant
Consists of the following cell types:
Xylem fibers
Xylem parenchyma
Vessel elements
Tracheids

22. Kinds of Complex Permanent Tissues
Xylem: cell types
Xylem fibers
appear like ordinary schlerenchyma fibers
Xylem parenchyma
structurally similar but much smaller than the ordinary parenchyma cells

23. Kinds of Complex Permanent Tissues
Xylem: cell types
Vessel elements
main conducting cells of the xylem
Elongated in shape and dead when mature
Heavily thickened cell walls
Have relatively large cavities or lumina which generally appear rounded in cross section
Vessel elements are attached end-to-end with their end walls perforated to form long conducting tubes (xylem vessels)
Perforation plate – perforated wall having one or more openings

24. Kinds of Complex Permanent Tissues
Xylem: cell types
Tracheids
simplest conducting cells of the xylem
dead cell when mature
elongated in shape and square-like in cross section with heavily thickened cell walls
Tracheary elements – consists of the vessel elements and the traceheids; have different types depending on how lignin is deposited on their cell walls

25. Cross section of a monocot stem
bundle sheath
companion cell
phloem
sieve tube
Cross section of a monocot stem
vessel
xylem
vessel
air space
vascular bundle

26. phloem fiber
phloem parenchyma
sieve tube
companion cell
vascular cambium
vessel
Tracheid (schlerenchyma)
xylem parenchyma
xylem fiber

27. Kinds of Complex Permanent Tissues
Main types of tracheary elements:
Annular type – thickening of the cell wall is in the form of rings
Spiral type – the thickening is in the form of a spiralling or helical structure
Scalariform – the thickening is ladder-like
Reticulate – the thickening is net-like
Pitted type – the uniformly thickened cell walls show the presence of more or less rounded depressions or pore-like structure (pitts) representing the non-lignifed portions of a wall

29. reticulate

30. Plant Trichomes Trichomes or epidermal hairs
appendages of the epidermal cells
may be unicellular or multicellular
glandular and non-glandular structures
Glandular trichomes – consist of living cells and produce secretions
Types: glandular and stinging trichomes
Non-glandular trichomes – consist of dead cells and non-secretory
Kinds: bristles, scales, stellate, and branched (dendroid)

31. Plant Trichomes Glandular Trichomes Glandular trichomes
produce secretions in enlarged terminal portions
Examples: ratilis, oregano and malvarosa
Stinging trichomes
Consist of enlarged base containing secretion from which projects a stiff, slender structure that ends in a sharp point
Example: lipang kalabaw

32. Plant Trichomes Non-glandular Trichomes
Bristles - stiff, sharp pointed hairs which may be barb-like protuberances along the sides as in lipa
Scales - flattened structure as in alingaro
Stellate trichomes – star-like structure as in ratilis and Mallotus
Branched trichomes (dendroid) – as in the velvet dock

34. Glandular trichomes

35. Glandular trichomes - Enlarge terminal portions

36. Glandular trichomes - Enlarge terminal portions

37. Non-gladular