Plants & Human Affairs
Cherries.wmf (7140 bytes) Plants & Human Affairs (BIOL106)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321;;

Wood Exercises & Study Questions

ObjectivesAt the conclusion of this exercise/unit you should be able to:

  1. distinguish between trees, shrubs, herbs and vines
  2. identify and give the function of the major cell types in the xylem
  3. describe the function and location of xylem and phloem in a woody plant
  4. define meristem and give examples
  5. identify the major features visible in the cross section of a tree, including rays, annual rings, grain, latewood (summerwood), early wood (spring wood)
  6. distinguish between ring-porous and diffuse-porous wooddistinguish between a hardwood and softwood
  7. recognize the wood of common species in central Minnesota
  8. describe the difference between radial, tangential and transverse sections
  9. describe the difference between quarter sawn and plain sawn boards.
  10. determine the age of a tree from its wood
  11. explain why trees have growth rings
  12. list at least 10 important wood products
  13. describe the uses of some common woods and wood products
  14. calculate wood density (ignore)


Wood Identification
     Each group will be given several numbered blocks of wood.  Match each block with the appropriate description.  You can also use a dichotomous key to help with your identifications.  As you study each particularly note the characteristic features and wood structures.  Confirm your identifications with me. 


_______ Ash

  • heartwood brown to grayish-brown
  • sapwood creamy �white
  • rings distinct, abrupt change from early to latewood
  • ring porous
  • rays barely visible to naked eye
  • handles, baseball bats, oars



_______ Red Oak

  • early wood pores in heartwood usually open
  • latewood pores visible
  • large rays visible to naked eye
  • furniture, flooring, millwork



_______ Black Cherry

  • semi-ring porous
  • sapwood whitish to light red
  • heartwood cinnamon-brown to dark reddish-brown
  • rings distinct, delineated by narrow band of pores in early wood
  • pores small and indistinct
  • rays plainly visible
  • wood dull, but takes fine luster when finished
  • color darkens with age
  • easily machined



_______ White Oak

  • early wood pores filled with tyloses
  • heartwood light-brown to dark-brown
  • large rays visible to naked eye
  • latewood pores small and indistinct
  • barrels and kegs, flooring, furniture
  • wood tough and resistant to wear



_______ Maple

  • rings distinct, delineated by dark line denser fibrous tissue
  • diffuse porous
  • small pores, uniform in size
  • sap wood wide, white or light
  • rays � barely visible or wide as or wider than largest pore
  • on tangential surface rays appear as very fine but distinct lines
  • furniture, flooring


  _______ Walnut
  • distinct growth rings
  • pores scattered, those in early wood readily visible
  • sapwood whitish to yellowish-brown (sometimes steamed to darken to match color of heartwood)
  • heartwood dark to chocolate-brown
  • furniture, cabinets, gun stocks, caskets
  • most valuable timber tree in the US

_______ Southern Pine

  • rings very distinct; delineated by pronounced band of darker latewood
  • contrast from early wood to latewood very pronounced
  • sapwood is nearly white to yellowish
  • heartwood is distinct, shades of yellow to orange to brownish
  • resinous odor
  • straight but uneven grain, medium texture
  • rays fine and not visible to naked eye
  • resin canals appear as whitish or brownish flecks distinct with handlens
  • pulpwood, plywood, dimensional lumber


  ______ White Pine
  • distinct, but not pronounced rings
  • each ring marked by a dark band in the latewood
  • resin canals - whitish flecks - visible in center of rings
  • rays very fine
  • construction, ship masts, millwork


Wood Density
: (not on exam)

  1. Measure the size of the wood block in cm.  Calculate the volume of the block.

  2. Weigh each block.

  3. Calculate wood density (gm/cm3). 

Annual Rings:
     Each year a new layer of wood is produced by a tree. By counting the number or layers, or annual growth rings, the age of the tree can be determined. The width of the ring provides an indication of the growing conditions in that year. Study a wood block or sketch.

Wood Cuts: 
     The three standard cuts of wood are transverse (cross sectional), radial and tangential.  Can you draw a section of wood and then:

Quarter Sawn vs. Plain Sawn Boards
     By examining the figure (= appearance) of a board, it is possible to tell if it was plain‑sawed or quarter‑sawed.

Heartwood and Sapwood:
    If given a transverse section of a tree, can you distinguish the heartwood and sapwood.  Sketch a pie shaped section of this specimen and label heartwood, sapwood, bark, annual ring, ray, vascular cambium.

Cell Types of Wood
    The two major water conducting cells in wood are tracheids and vessels. 

Red pine__________   Sugar maple__________
Oak__________   Blue spruce__________

Wood Porosity: 
    The vessels in wood are also termed the pores.  The distribution of vessels in wood is species-specific and can be useful for identifying wood.  Ring-porous refers to wood in which the vessels are arranged parallel to the ring.  In diffuse-porous wood, the vessels are scattered throughout the ring. Using the wood samples provided, do you observe any vessels or pores in the wood of spruce, oak or pine?

Wood Forensics:
    Wood played a major role in solving the murder of Charles Lindbergh's infant son.  Describe this case and the type of information derived from wood that was used to solve it.

    Vessel cells can become plugged by outgrowths from the parenchyma cells called tyloses.  These bubble-like structures can accumulate a variety of resins and other materials that effectively plugs up the vessel.  Tyloses are usually formed when sapwood changes into heartwood, but can be formed at any time (Sharp, 1990).  Tyloses are common in white oak and black locust and a characteristics of wood used in tight cooperage (barrel making). 

    Obtain a twig (1/4 to 1/2 inch diameter) from red oak and white oak.  Attach a rubber hose to one end of the twig and attach the other end to a water outlet.  Slowly turn on the water and observe the end of the twig.  On which twig, in either, do drops of water appear?  Explain why.  Which wood would make better barrels? 

Some Study Questions:

  1. If given a log, can you show where to make the following cuts: transverse (cross section), radial, and tangential?
  2. Can you identify on a piece of wood, whether it has been cut transversely, radially or tangentially?
  3. If you drive a nail into a tree, list the sequence of cells/tissues that you would encounter from outside to inside.
  4. Compare and contrast veneer & plywood.
  5. What are the dimensions of a 2 x 4?  Explain.
  6. Can you answer questions such as those in the website quiz for Chapter 18 or 3?
  7. Can you define/use the following terms:

annual ring
cork (phellum)
cork cambium (phellogen)

inner bark
outer bark
plain sawn
quarter sawn

spring wood
summer wood
vascular cambium



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Last updated:  12/13/2005 / � Copyright  by SG Saupe / URL: