Wood Anatomy and Growth for Exam 1 Review

Even, coarse

Early/latewood transition

Growth Ring placement

Close, dense, narrow

Vessel

A structure in xylem tissue that conducts water and provides mechanical support.

Apical meristem

The growing region at the tips of roots and shoots in plants.

Lumen

The central cavity of a cell in xylem or phloem tissue.

Quarter sawn

Wood sawn at a radial angle to the growth rings, producing a distinctive grain pattern.

Flat sawn

Wood sawn parallel to the growth rings, resulting in a different grain pattern than quarter sawn.

Middle lamella

A pectin layer that cements adjacent plant cells together.

Primary wall

The initial cell wall layer formed during cell growth.

Figure

The visual pattern created by growth rings and rays on the surface of wood.

Ray fleck

A distinctive figure caused by the rays in wood being cut at an angle.

Cellulose (Chemical Structure)

Consists of 50% glucose units bonded in a Beta 1-4 linkage, with microfibrils having 10,000 DP.

Hemicellulose (Composition)

Comprises 20-30% of the cell wall and includes branched sugars like xylose, galactose, and mannose.

Lignin (Composition)

Makes up 20-30% of the cell wall and consists of phenylpropane units that provide rigidity.

Anticlinal Division

Production of new initials byradial partitioning

S1

low angle of cellulose microfibrils

S2

Steep angle of microfibrils, thick layer dominates behavior

S3

low angle of cellulose microfibrils similar to S

Why does wood shrink and swell with moisture changes?

Water penetrates the amorphous regions of microfibrils andexpands the cellulose network especially the S 2 layer

Term to describe the arrangement of longitudinalcells

Cross, Interlocked

Planes of reference

end grain, side grain

Figure type

bird's eye, fiddleback, quilted

Pore Size

fine, open

What is the Cell Wall made from?

Elements; H, O, C
Primary Molecules:Cellulose: 50% Glucose chain bonded in Beta 1-4 linkage; Microfibrils have10,000 DP
Hemicellulose: 20-30%, branched sugars, (xylose, galactose, mannose etc)Bonds both Cellulose and Lignin
Lignin: 20-30% Phenyl- propane, gives rigidity to cell wall
Secondary Chemicals
Extractives; 1% -5%; Heartwood only!
Ash; 1% Earth elements: calcium, magnesium, etc

Cellulose

A polysaccharide consisting of glucose units and a major component of plant cell walls.

Lignin

A complex organic polymer that provides rigidity to the cell walls of plants.

Hemicellulose

A polysaccharide that binds to both cellulose and lignin in plant cell walls.

Heartwood

The older, non-living central wood of a tree that provides structural support.

Sapwood

The younger, outer wood of a tree that conducts water and nutrients.

Tracheid

A type of elongated cell in xylem tissue that transports water and minerals.

Growth ring

Annual ring in wood formed by the contrast between earlywood and latewood.

Cambium

A layer of meristematic tissue in plants that produces new cells for growth.

Meristematic tissue

Plant tissue containing undifferentiated cells capable of cell division.

Cell wall

A rigid layer surrounding the cell membrane, providing structural support.

Ray cells

Parenchyma cells in wood that transport materials radially within the tree.

Pits

Small areas in the cell wall that allow for water and nutrient movement between cells.

Orthotropic Material

Material with three mutually perpendicular axes of symmetry.

Rift sawn

Wood sawn at an angle slightly off the radial direction, between quarter sawn and flat sawn.

Secondary Wall

A thicker cell wall layer formed inside the primary wall for additional support.

Elements

Basic substances that make up the cell wall, including hydrogen, oxygen, and carbon.

Fusiform Initial

These are long rounded cells. These divide repeatedly to form either new cambial initials or new xylem and phloem cells

Ray Initial

These are short rounded cells. Division of these creates either new xylem or phloem rays or new ray initials.

Periclinal Division

Division parallel to the stem surface in a tangential plane that results in formation ofeither xylem or phloem cells