07 PPT NOTES Vascular Plant Growth

Phloem

The vascular tissue responsible for the transport of nutrients and carbohydrates produced by photosynthesis.

Pith

Central part of the stem, involved in storing nutrients and water.

Xylem

The vascular tissue responsible for the transport of water and dissolved minerals from the roots to the rest of the plant.

Dermal cells

Cells that form the outer protective layer of the plant.

Auxins

Plant hormones that promote root formation and control other growth processes.

Cytokinins

Plant hormones that promote shoot formation.

Cork Cambium

A tissue that produces cork cells, forming part of the bark of a plant.

Apical meristem

A region at the tip of a plant shoot or root that contains actively dividing cells and is responsible for primary growth.

Secondary growth

The increase in thickness (girth) of stems and roots in woody plants, involving cell division in the vascular cambium.

Heartwood

The innermost, oldest wood of a tree that is no longer involved in transport of water and nutrients.

Sapwood

The younger, outer layer of wood that is involved in the transport of water and nutrients.

Stomata

Small openings on the surfaces of leaves that allow for gas exchange.

Vascular cambium

A layer of tissue between the xylem and phloem that contributes to secondary growth.

Storage roots

Roots that store carbohydrates and nutrients for the plant.

Tendrils

Specialized structures that help plants cling to supports.

Rhizome

A horizontal underground stem that can produce new shoots and roots.

Stolons

Above-ground horizontal stems that can produce new plants at the nodes.

Cortex

The region of the root between the epidermis and the vascular tissue.

Guard cells

Cells that surround stomata and regulate their opening and closing to control gas exchange.

Bundle sheath cells

Cells that surround vascular bundles in plants, often associated with photosynthesis.

Fibers

Long, slender cells in plants that provide structural support.

Embryonic cells

Undifferentiated cells that have the potential to develop into different types of plant tissues.

Periderm

A protective tissue that replaces the epidermis in older stems and roots.

Roots, Stems, Leaves

What are the major plant organs?

Roots

The part of the plant that anchors it to the ground, absorbs water and nutrients, and can store carbohydrates.

Stems

The part of the plant that supports leaves and flowers, transports nutrients and water between roots and leaves, and can store nutrients.

Leaves

The part of the plant primarily responsible for photosynthesis, typically consisting of a flattened blade and a petiole that connects to the stem.

They lack the complex structure and vascular tissue

Why are microphylls of nonvascular plants not considered leaves?

Storage, Aerial, Prop, Pneumatophores, Buttress.

What are the different types of roots?

Storage roots

Type of root that stores nutrients and starch Ex: Potatoes

Aerial/Strangler roots

Type of root that helps the plant gather sunlight

Prop roots

Type of root that prevents erosion by anchoring the plant.

Pneumatophores

Type of root that helps the plant get oxygen (lungs of the plant)

Buttress roots

Shallow roots that prevent the plant from falling over

Rhizomes, Tubers, Stolons, Bulbs.

What are the different types of stems?

Rhizomes

Underground stems that store nutrients and can produce new shoots, allowing for vegetative reproduction.

Tubers

The ends of rhizomes that store nutrients.

Stolons

Type of stem that extends above the ground and along the surface Ex: Strawberries

Bulbs

Type of stem that stores nutrients Ex: Onions.

Tendrils, Spines, Storage, Reproductive, Bracts.

What are the different types of leaves?

Tendrils

Modified leaves used for climbing to reach more sunlight

Spines

Leaves that are used for protection ex: cacti

Storage leaves

Leaves that store nutrients as starch Ex: Aloe.

Reproductive leaves

Individual leafs that can grow into a whole new plant.

Bracts

Flower-looking leaves, attract pollinators.

Indeterminate vs. Determinate growth. Apical base polarity. Varying levels of maturity depending on the region of the plant.

What are 3 ways that plant growth differs from animal growth?

It would remain at eye level because Apical-Base Polarity causes growth from the root and the shoot.

If you carved your name into a tree at eye level and returned many years later, what level would the carving be at? Explain.

Procambium → primary vascular tissues (xylem and phloem) and vascular cambium → secondary vascular tissues (xylem and phloem)

Protoderm → Epidermis

Ground meristem → Cortex, Pith, and Non-vascular tissues (Parenchyma, Collenchyma, Sclerenchyma cells)

What are the three main meristems of the SAM? What do each of them then differentiate to? Do any of these tissues (after differentiation) then make more tissues of their own? What are these “secondary growth” tissues?

Parenchyma cells

Non-vascular cells differentiated from the ground meristem. Metabolic functioning cells.

Collenchyma cells

Non-vascular cells differentiated from the ground meristem. Early structural support to young tissues, alive cells, contain lignin which makes wood hard.

Sclerenchyma cells

Non-vascular cells differentiated from the ground meristem. Structural cells, contain thick, lignified walls, unalive.

Anti-clinal

What kind of cell division does the procambium do?

Mucilage protection and root cap.

Describe two mechanisms that protect the RAM when moving through soil.

The root needs to extend deeper into the soil via ACD. And it needs to continuously regenerate the root cap to protect it as it pushes through the soil via PCD. The shoot apical meristem does not need PCD to continuously regenerate it after damage because it grows into the air.

Why does the root apical meristem have both anti-clinal division (sideways) and peri-clinal division (vertical) in the first layer of cells, while the shoot apical meristem has only anti-clinal division in the first layer?

Anti-clinal division

A type of cell division that occurs in the root apical meristem and shoot apical meristem where cells divide perpendicular to the surface, expanding the root's length.

Periclinal Division

A type of cell division in which cells divide parallel to the surface, contributing to the increase in girth of the root or shoot.

The cell wall becomes more acidic. This signals expansins to cut polysaccharides in the cell well. Water will enter the cell wall due to a high H+ concentration which will allow the cell wall to elongate.

After plant cells experience Auxin, they begin to pump H+ atoms in to their cell wall. What does this lead to? How does water pressure play a role? (need to learn water potential in plants before you can answer this)

Phototrophism

The growth of plant organs in response to the direction of light.

Central stem grows more than the side stems due to a higher Auxin concentration.

What is apical dominance? What hormone is responsible for it? How can apical dominance produce fractals?

It reduces auxin levels so side stems can grow

Why does cutting off the top of a tree cause it to become more shruby?

It releases Auxin which encourages the plant to establish a healthy root system.

Why is it beneficial to prune some shoots when repotting or transplanting a plant?

Xylum, Phloem, Cortex, Pith.

Identify all major tissues of wood.

Procambium, Vascular Cambium, Cork Cambium

Identify all major meristems of wood.

Cork Cells, Cork Cambium, Phloem

What types of cells is bark made out of?

Suberin

What makes cork impermeable to water?

Heartwood is the innermost, oldest part of the wood. Does not transport nutrients and water. Provided support structure and contains resins and tannins, making it darker and more resistant to decay.

Sapwood is the outer living layer of the wood that conducts of water and nutrients. It is lighter and surrounds the heartwood.

What is the difference between heartwood and sapwood?

Represents one year of growth.

1. Spring Growth: Growth is prioritized. The wood produced during this time is lighter in color and has larger cells.

2. Summer Growth: Sexual maturation is prioritized. The wood produced is denser and darker in color with smaller cells.

What are the rings within the trunk of the tree (tree rings)? How are they formed/what do they show?

Secondary growth.

1. Shoot Apical Meristem (SAM)↓

2. Primary Meristem

   • Protoderm → Epidermis (primary covering)

   • Ground Meristem → Cortex (primary tissue)

   • Procambium → Primary Xylem and Phloem (transport tissues)↓

3. Secondary Growth Initiation

   • Vascular cambium develops between the primary xylem and phloem

   • Cork cambium (phellogen) forms from the pericycle or outer layer of the vascular cambium↓

4. Formation of Cork Cells (Phellem)

   • Cork cambium produces cork cells which differentiate to form the outer bark

   • Cork cells become dead and provide protective functions

Is a cell on the outer bark, also known as the cork, primary or secondary growth? Explain how that cell got here starting from the shoot apical meristem using a flow chart (Shoot apical meristem → ? → ? → ? etc). Include as many intermediate steps as you can

Provide surface area for absorbing sunlight and exchanging gases

What is the primary function of leaves in vascular plants?

Vascular tissue

Which tissue type in plants is responsible for transporting water and minerals?

Increase the surface area for absorbing water and minerals

What is the role of root hairs in plants?

Secondary growth

What type of growth increases the diameter of stems and roots in woody plants?

Roots

Which plant organ is primarily responsible for anchoring the plant and absorbing water and minerals?

Regions in plants that generate new cells for growth

Meristem

lengthens roots and shoots

Primary growth

The process that increases the diameter of stems and roots in woody plants

Secondary growth

Vascular cambium → secondary xylem and phloem, Cork cambium → cork.

What are the secondary growth tissues and meristems?