1. Objectives:
List and describe the major plant organs their structure and function
List and describe the major types of plant cells and their functions
List and describe the major types of plant tissues, identify their locations and describe their functions.
Identify and describe the external parts of a monocot and eudicot plant.
Identify and describe the distribution of tissues in the stem, root, and leaf of a monocot and eudicot plant.
Identify, describe, and explain the changes that occur in a eudicot stem as it matures.
Explain the relationship between the distribution of tissues in the leaf and the functions of these tissues.

2. Plant Tissues and Organs

3. Major Plant Organs
Flowering plants possess three kinds of vegetative (non-reproductive) organs: roots, stems, and leaves. The flower is the reproductive organ of the Angiosperms.
Shoots consist
of stems and
leaves.
Functions are photosynthesis, support and transport
Roots anchor
and absorb
water and
minerals and
provides nutrients for the shoot and
can be an area of storage

4. Organ Functions
The shoot system of a plant consists of the stems and the leaves, as well as flowers.
Leaves are the main sites of photosynthesis in plants.
Stems hold and display the leaves to the sun and provide connections for the transport of materials between roots and leaves. It may also serves as an area of storage.
A node is the point where a leaf attaches to a stem.
Regions of stem between nodes are the internodes.
Flowers are modified leaves structure which support the microsporangia and megasporangia gametophyte generations and are involved in plant sexual reproduction. Flowers are usually located apically or a the end of a stem.
The root system provides support, storage and nutrition.

5. Plant Cell Types (Support and Storage)
Parenchyma cells:
numerous
thin walls and large central vacuoles
the photosynthetic cells in leaves
filled with chloroplasts
mesophyll cells.
Some store lipids or starch (potatoes)
Collenchyma cells:
supporting cells that lay down primary cell walls that are thick in the corners
provide support to leaf petioles, nonwoody stems, and growing organs
compose the cortex and pith tissues of the root and stems

6. Plant Cell Types (Support)
Sclerenchyma cells:
main supporting cells of a plant
thick secondary cell wall
contains lignin -a component of wood
two types:
elongated fibers
variously shaped sclereids
Fibers often organize into bundles.

7. Plant Cell Types Vascular (Transport)
Xylem
contains conducting cells called tracheary elements.
Tracheids are evolutionarily more ancient tracheary elements found in gymnosperms.
tracheary elements and tracheids undergo apoptosis(die) leaving only their cell walls to become functional
Vessel elements: similar to tracheids (tracheary elements) but larger and are laid end to end - also formed from dead cells - Flowering plants have both!
Phloem
Conducting cells called seive tube members
are alive
are arranged end-to-end and form long sieve tubes, which transport carbohydrates and other materials.
The plasmodesmata in sieve tube members enlarge as they mature
filled with sieve tube sap (water, sugars, and other solutes).
The sieve tube members have adjacent companion cells
Companion cells retain all their organelles and regulate the performance of and support the sieve tube members

8. Xylem and Phloem Cell Types

9. Plant Tissues
A tissue is an organization of cells that work together as a functional unit.
Parenchyma cells make up parenchyma tissue, which is a simple tissue.
Xylem and phloem are complex tissues; they are composed of a number of different cell types.
Tissues are grouped into tissue systems that extend throughout the body of the plant from to form the various organs of the plant.
There are four plant tissue systems: vascular, dermal, ground and meristemic.

10. Plant Tissues

11. Vascular Tissue xylem and phloem
phloem transports carbohydrates from sites of production (sources such as leaves) to sites of utilization for energy or where it is being stored (sinks) elsewhere in the plant.
xylem distributes water and mineral ions taken up by the roots to the stem and leaves.

12. Dermal Tissue outer covering of the plant.
All parts of the young plant body are covered by an epidermis, which is a single layer or multiple layers of cells.
epidermal cells and other specialized cells such as guard cells.
The shoot epidermis secretes a layer of wax-covered cutin, the cuticle, which helps retard water loss from stems and leaves.

13. Ground Tissue primarily parenchyma tissue
storage, support, photosynthesis, and the production of defensive and attractant substances (oils and toxins)

14. Meristems (Plant Stem Cells)
The localized regions of cell division in plants, called meristems, are forever embryonic. They have the ability to produce new cells indefinitely.
When a meristem cell divides, one daughter cell develops into another meristem cell, and the other differentiates into a more specialized cell. The meristem gives rise to all plant cell and tissue types.
There are two types of meristems in Angiosperms:
Apical meristems give rise to the primary plant body, which is the entire body of many plants.
Shoot and Root
Apical meristems are responsible for primary growth, which leads to elongation and organ formation.
Lateral meristems give rise to the secondary plant body.
Lateral meristems t give rise to the tissues responsible for this thickening.
Intercalary – found in grasses

15. Location of Meristematic Tissues

16. Growing Eudicot Stem Structure
These
tissues form
a vascular
bundle. In
woody plants
they grow
together and
fuse to form a
continuous ring
creating annual
growth rings.

17. Mature Eudicot Stem
Secondary growth increases the diameter of stems and roots.
Secondary growth results from the activity of vascular and cork cambia.
Vascular rays connect storage parenchyma to the sieve tubes of the phloem.
Only eudicots have a vascular cambium and a cork cambium and thus undergo secondary growth.
Cross sections of most tree trunks in temperate zone forests have annual rings.
Annual rings form due to differential rates of growth in spring (when water is plentiful) and in summer.
Wood that is no longer conducting water is known as heartwood.
Sapwood is wood that is actively conducting water and minerals in the tree.

18. Root Tip Structure

19. Root Structure (Monocot vs Eudicot)

20. Root Structure (Monocot vs Eudicot)
Eudicots have their Monocots have pith
xylem centrally located tissue that is centrally
usually in an X formation located. Xylem cells
no pith is present! arranged in a ring.

21. Leaf Structure
Leaf anatomy is adapted to carry out photosynthesis, limit evaporative water loss, and transport the products of photosynthesis to the rest of the plant.
The two zones in leaf parenchyma that photosynthesize are the palisade mesophyll and the spongy mesophyll.
Within the mesophyll is air space through which CO2 can diffuse to the photosynthesizing cells.
Veins supply mesophyll cells with water and minerals, and they transport the products of photosynthesis to the rest of the plant.
The epidermis of the leaf is the outermost cell layer, which is covered by a waxy cuticle. The epidermis functions to keep water and photosynthetic products in the leaf.
Guard cells allow controlled gas exchange through pores in the leaf (the stomata).

22. Leaf Structure