FRST Lesson 2- Xylem and Phloem

Xylem

• Transports water and nutrients from roots to stems and leaves

• Only goes one-way there are no end walls between cells, and thick walls are stiffened with lignin.

Carbon sequestration definition

• When Carbon from CO2 is trapped into the wood

Phloem

• Conducts sugars and other metabolic products throughout the plant and downward from the leaves

• Flow of fluids can go both ways

• Cells have end walls with perforations (small holes)

How does the lateral movement of water and nutrients occur

Through xylem

How does sugars and other metabolic products move downward from the leaves

• Phloem

Vascular cambium

New wood (xylem) is made here, this part of wood originates from being is a thin layer of cells that retains the ‘magical’ property of being table to repeatedly divide.

What happens after the vascular cambium expands

• Cell walls thicken and lignify and then die

What does divisions in the Vascular Cambium create?

• Divisions to form new initials (Fusiform initials and ray initials)

• Divisions to produce new xylem (wood) and phloem cells

Fusiform initials

• Cells in the vascular cambium that divide to form secondary phloem and xylem.

• Elongated cells that are arranged as bricks

• Produce all vertical cells

Ray Initials

• Rectangular, and shorter

• Produces all horizontal cells

Periclinal Division of Cambial Fusiform initials

• This division in the vascular cambium is oblique or pseudotransverse to the length of the initial

T/F Fusiform Initials in the vascular camibium are the only ones that divide

True

T/F Anticlinal dvivision of fusiform initials creates new wood and ‘bark’?

False, periclinal division creates new bark and wood tissues

List the events leading to the formation of secondary xylem(except parenchyma) in the vascular cambium?

(I Eat The Last Donut)

A) Initiation
B) Enlargement
C) Thickening of cell wall
D) Lignification
E) Death

Order of taxa in biology

Domain King Phylum Class Order Family Genus Species

Dear King Phillip Came Over For Good Soup

Soft hardwoods

Balsa Paulownia; Poplar and Wilow

Barmy Philip Prefers Wood

Changes in Dimensions of Cells During Enlargement Phase: Diameter

• Particularly evident in the radial direction in earlywood tracheids in conifers and radially and tangentially in vessels hardwoods

Changes in Dimensions of Cells During Enlargement Phase: Length

• Particularly evident in softwood tracheids (10-15%) and hardwood fibres (20-46%)

Wood cross section (fill in the blank)

Clarinet wood conservation

• Making existing clarinets last longer

• Developing apparatus to simulate long term playing of clarinets

• Develop treatments to stop cracking of barrels

Look for alternative woods

Currently testing two different woods

• Currently making a composite material consisting of sawdust and resin

Where is the Grenadilla tree found and what is it used for?

• It is found in Senegal, Eritrea, Tanzania, and South Africa.

• The world most expensive wood and is very rare, great efforts are being made to conserve it.

• One of the two woods used to make Clarinets.

Where is the Cocobolo tree found and what is it used for?

• Found in the Pacific regions of Central America, ranging from Panama to south western Mexico.

• Is increasingly rare and seldom found outside national parks.

Different types of cells in wood

• Ray cells and longitudinal/tracheid cells

Vessel elements

• (Conduct water) - joined end to end

Fibres

• Elongated, thick-walled cells (give strength)

Axial parenchyma (or jus parenchyma)

• Soft tissue - (storage)

Rays

• Storage

Who was the famous Swedish scientist who developed the binomial system of naming species?

• Carl Linnaeus

How does the vascular cambium keep up with growth in size of the stem (Bailey)

• Though the increase of the cambial initials during the earlier stages of the enlargement of certain plants, is by no means a negligible factor; the rapid increase in girth of the lateral meristem must in general be due largely to a progressive increase in the number, rather in the size of its constituent cells.

How are ray initials created?

• Transverse divisions within fusiform initials (blue arrows)

• Intrusive growth of fusiform initial into two (red arrows)

Periclinal cell division

• Cell divisions that occur parallel to the surface of a plant, adding new cells to the plant’s girth (circumference of its stem, or the measurement around the outside of its trunk.)

Lignification

• Converting wood or woody tissue, strengthen plant cell walls by depositing lignin polymers in them.

• Complex process that occurs only in higher plants

What does the first periclinal cell division produce?

• One secondary cell (xylem or phloem and one cambial cell)