1. Cells and Tissues of the Plant Body

2. Tissue Systems in Plants
A tissue is a group of cells that forms a structural and functional unit
There are three main tissue systems in plants:
Ground tissue system
used for photosynthesis, storage, and support
Vascular tissue system
Intricate plumbing system that conducts water, minerals, and food
Dermal tissue system
Covering of the plant body

3. Ground Tissue System This makes up the most of an herbaceous plant
This system is composed of three tissues:
parenchyma
collenchyma
sclerenchyma

4. Parenchyma Tissue
Found throughout the plant body and is the most common type of cell and tissue
The soft parts of the plant are mostly parenchyma
Ex: edible part of an apple or potato

5. Parenchyma Tissue
These cells contain chloroplasts to perform photosynthesis
Starch grains, oil droplets, water, and salts can be stored in parenchyma cells
Resins (sap), hormones, enzymes, and nectar can be secreted by these cells
These cells have the ability to differentiate into other kinds of cells when a plant is injured (similar to a stem cell in the human body)

6. Collenchyma Tissue
This is a flexible tissue that provides support in soft, nonwoody plants. This allows for plants to grow upward and receive adequate sunlight.
These cells are elongated and have thicker corners
The strings of celery have collenchyma tissue

7. Sclerechyma Tissue
These cells have primary and secondary cell walls which means they have two support systems for the plant
The secondary cell walls become strong and hard because of thickening of the wall around the cell.
When sclerenchyma tissue provides support, the cells are often dead.
Two types: sclereids and fibers

8. Sclerenchyma Tissue Sclereids: Fibers short cells that vary in shape
Common in shells of nuts or the stones of fruits
Ex: gritty texture of pears are sclereids
Fibers
Long tapered cells that occur in groups or clumps
Abundant in the wood, inner bark, and veins of leaves

9. Vascular Tissue System
Embedded in the ground tissue and transports materials through the plant
Xylem and Phloem are the two main tissues within this system

10. Xylem and Phloem
Xylem: moves water and dissolved minerals from the roots to the stems and leaves
Contains four cell types: tracheids, vessel elements, parenchyma cells, and fibers
Phloem: moves food (carbohydrates) throughout the plant and provides structural support
Contains four cell types: sieve-tube elements, companion cells, phloem fibers, and phloem parenchyma cells

11. Dermal Tissue System Provides a protective covering for plant parts
In herbaceous plants this is the epidermis
In woody plants, an epidermis will split apart creating a periderm that is stronger and replaces the role of the epidermis

12. Epidermis
Epidermis: tissue made of unspecialized cells with guard cells and trichomes included
Cells are thicker on the outside for protection
Release a waxy layer called the cuticle that covers surface to reduce water loss
Between two guard cells are stomata that allow for gas exchange
Contains trichomes which are outgrowths or hairs

13. Periderm
Periderm: the outmost layer of cells covering a woody stem (the outer bark)
Composed mostly of cork cells and cork parenchyma cells
Cork cells are heavily coated with suberin which is waterproof helping to reduce water loss

14. Plant Meristems In order for plants to grow, they must go through
Cell division
Cell elongation
Cell differentiation
In animals, these processes occur everywhere, however in plants, there are only particular locations for growth, meristems

15. Two Kinds of Growth
Primary growth: an increase in the length of a plant
All plants have this type of growth
Secondary growth: an increase in the girth (horizontal) of a plant
Only woody plants have this type of growth

16. Primary Growth
Primary growth occurs at apical meristems or areas at the tips of roots and shoots.
Roots have a protective layer of cells called the root cap that protect the root during the division of cells

17. Secondary Growth
Secondary growth occurs at the lateral meristems which occur at the entire length of stems and roots
This growth is what allows for trees to form rings each year