1. Bellwork: How do the main functions of a plant’s tissue systems differ?

2. Specialized tissues in plants
Section 23.1 – Plant structures and function

3. What are the three principal organs of seed plants?
Roots
Anchor plants, hold in soil, prevent erosion, help form mutualistic relationships with bacteria and fungi that help root absorb water and nutrients, help transport these things to other parts of the plant, store food and provide support.
Stems
Support system, host transport system, defense system against predators, produce leaves and reproductive organs,
Leaves
Main photosynthetic organ, large surface area for capturing sunlight, have adaptations against water loss,

4. What are the main tissue systems in plants?
Dermal tissue
Covers a plant like skin
Vascular tissue
Act as a plants bloodstream
Ground tissue
Produces and stores food

5. Dermal Tissue The protective outer covering of the plant
In young plants - one layer of cells called the epidermis
Covered with a thick waxy layer called the cuticle
Protects against water loss
Some have trichomes - aid in leaf protection
In older plants, epidermis may be several layers thick and covered with bark
In roots, root hairs are an example of dermal tissue

6. Vascular tissue Support plants body and transport water and nutrients
Xylem – water
Called tracheids
Found in all seed plants
Long and narrow
Xylem is made up of dead cells – lignin in cell walls resists water and provides strength
Opening in walls connect neighboring cells
Pits (thinner regions) allow water to flow to ground tissue by diffusion

7. Xylem continued… Angiosperms do not just contain tracheids
Vessel element – wider than tracheid and stacked on top of each other
After cells mature and die, cell walls are left with slit like openings allowing movement of water
In some cases you can be left with a continuous tube

8. The Phloem Unlike Xylem, Phloem cells are alive at maturity
Main cells are called sieve tube elements
Arranged end to end
End walls have many small holes – allowing nutrients to move from cell to cell
As they mature, sieve tube elements loose their nuclei and many organelles
Remaining organelles sustained by companion cells
Surround sieve tube elements
Support phloem and aid in the movement of material in and out

9. Ground Tissue Tissues that are neither vascular or dermal
Main functions are to:
Produce and Store sugars
Contribute to physical support of the plant
From the edible part of most plants
Most consist of Parenchyma
Thin cell wall, large vacuole and thin layer of cytoplasm
In leaves, these cells contain chloroplasts for photosynthesis
Collenchyma form another type of ground tissue
Strong flexible cell walls that help support plant organs
Example – celery stem
Sclerenchyma – thick rigid wall – make up seed coats
Used to make rope from hemp
Found in nut casings

10. Ground tissue overview

11. What is a meristem?
A region of unspecialized cells in which mitosis produces new cells that are ready for differentiation
Explains why plants unlike animals never stop growing!
Apical meristem – tip of stem or root (As tip is called apex)
All start out similar, but over time will differentiate into dermal, vascular or ground tissue

12. Meristems and flowers
Cones and flowers (reproductive organs) are also formed from meristems
Development begins with a change in the pattern of gene expression changes in a stem’s apical meristem
Transform apical meristem into floral meristem
Produces flower tissues

13. Key points questions What are the three main organs of a seed plant?
What are the three main types of tissues?
How do the functions of the different tissues differ?
What is a meristem? What is its function?
How do meristems relate to plant cutting? How does taking a cutting work?