Studied by 0 peopleType of cell responsible for hardwoods being described as “porous”
Vessels
2 types of cell configuration that comprise a growth ring
Early wood and late wood
3 compounds that compose cellular structures
Cellulose, Hemicellulose, Lignin
Bundles of cellulose and hemicellulose that are oriented in the same direction in a layer of the secondary cell wall
Microfibrils
Openings between conductive and/or parenchyma cells that permit exchange of water and/or food products
Pits
Which xylem has a more orderly appearance?
Softwoods
Which cell type is most common in softwoods?
Trachied
A vessel is composed of what cell type?
Vessel Elements
Ring porous
Diffuse porous
Semi-diffuse porous/semi-ring porous
Which has thicker cell walls in softwoods, late wood or early wood?
Latewood
Wood exhibits different properties when viewed from different angles
Anisotropism
Made of parenchyma cells, living part of the wood where water and nutrients are transported
Sapwood
Dead parenchyma cells
Heartwood
Cellulose role in wood production
Provides structural support (in cell wall)
Hemicellulose role in wood production
Primary component of middle lamella (void between cells) of cell, provides support and structure to the cell wall
Lignin role in wood production
Acts as an adhesive (glue) in cell wall, holding together cellulose and lignin, reason for stiffness of wood
Why mature wood is longitudinally stable?
Because of the microfibril angles in the three secondary walls
Simple pit
Parenchyma to parenchyma
Border pit
Conductive to conductive
Half border pit
Parenchyma to conductive
Pit membrane modification in softwood bordered pit pairs
Torus/margo found mostly in softwoods
What causes differences in texture?
Size of vessels, diffuse porous (fine) vs. ring porous (coarse)
Tracheids role in softwood structure
Tracheids compose 95% of wood cell types in softwoods, provides structure and moves xylem sap
Resin canals (and epithelial cells) role
Resin canals move and put out sap, epithelial cells form resin canals (not present in hardwoods)
Cells arranged in single row
Uniseriate
Wide in middle and thinner at each end
Fusiform
Made up of one type of ray cell: all ray procumbent cells or all ray upright cells
Homocellular
Made up of 2 types of ray cells: ray procumbent cell and ray upright cell found in the same ray
Hetrocellular
Types of cells in hardwoods
Parenchyma, fibers, vessel elements, tracheids
Vessels role
Made of vessel elements, move xylem sap (water)
Tyloses role
Parenchyma cells balloon out cytoplasm after death to fill vessels, forming tyloses
Parenchyma role
Starch storage
Trachieds role
Move water
Wood produced in lateral cambium is close to apical meristem
Juvenile wood
What can be done to make juvenile wood less of a problem in wood utilization?
Make stands denser to get lateral cambium away from apical meristem
Produced when main stem or a branch is subjected to unusual orientations or mechanical stresses
Reaction wood
Two types of reaction woods and where do they occur with respects to species group and location on the tree?
Compression on softwood (inside bend)
Tension on hardwoods (outside bend)
Why is each type of reaction wood longitudinally unstable?
G-layer is loose and provides no reistance to shinkrage or swelling in other secondary cell wall layers
Note
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