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Tuesday, March 26, 2013

Wood Science 101 (8) - Wood Species Identification and Macrophotography

One question that wood scientists get asked more than any other is..."What type of wood is this?" Sometimes the answer is easy, but often it isn't.

Tree identification is simple by comparison. With a tree, you have leaves, needles, and/or twigs, which are usually a dead give-away of a tree's species. Then, you have identifiers such as whether the leaves are alternating or opposite, the appearance of the bark, and even where the tree is growing. All these factors can also be referenced on a dichotomous (this-or-that) key, which asks you to compare traits until finally, you wind up with the right answer.

Wood is tougher, generally. With wood, you're usually handed a block of wood, typically finished with a stain and/or sealant, or you're asked what kind of wood is this table, or that cabinet, or this old walking stick. So references are limited to color, grain, defects, texture, and sometimes smell...and all of these can be deceiving.

For instance, most people have little trouble identifying an oak table or chair. Oak has a distinctive look, due to the presence of rays, which are darker, fingernail-sized or larger, streaks in the lighter wood. And regardless of the direction of the grain, these rays are apparent and give the wood its unique rustic oak look.



Oak, oak, and oak.  http://www.artisansofthevalley.com



But wood scientists and collectors know that there are hundreds of different oak species, and identifying one from another is next to impossible for most of us. Even wood identification guru Bruce Hoadley admits in his book Identifying Wood that "Separating the many oak species is another matter - the best we can do is assign the wood to either the red oak or the white oak group." Generally, the rays tend to be shorter in the red oaks.

As another example of commonly mistaken identity at an even higher taxonomic level, it's also difficult to tell black cherry from Pacific red alder or "Chinese Cherry" or similar other tropical species that are marketed as cherry. Overseas furniture makers often take advantage of this difficulty to market their furniture as "cherry" or whatever other name is most popular with the local populations.
Cherry, alder, or other? http://www.wallbedsbywilding.com


This difficulty in identification, compounded by different woodworking and finishing techniques, means that even the experienced wood connoisseurs can and will make mistakes.  And why truly accurate wood identification requires microscopic examination and a knowledge of the cellular structure of wood. That is what makes the art and science of wood identification fascinating to wood collectors and a nightmare for wood technology students.

This was all brought back to me by the following series of videos. A distinguished member of the International Wood Collectors Society, that very same group I visited last month at their Florida convention, has posted these videos demonstrating a technique he has developed for preparing and photographing wood samples under magnification. His name is Jean-Claude Cerre, and his photographs are stunning. The videos are freshly uploaded, and according to YouTube, have only been viewed by a couple of hundred folks. So you, Go Wood reader, are among the very first in the world to see these wonderful images.

In this first video, he explains why he has undertaken this task and shared it with the world. During this introduction, various photographs of his work are shown. All are photographs of the transverse, or cross-section view of the wood, for, as Mr. Cerre explains in the video, "the transverse structure of wood is like a fingerprint in humans." The transverse section is the equivalent of looking down at the top surface of a stump of a tree, or at the end of a piece of lumber...you're looking into the open tube-end of the wood cells that were discussed in our last post in this series about water movement in a tree.

Since the samples are all identified in the video by their scientific names, I thought you would like an easy way to reference them to their common names. Here is a list of the samples in the order they are shown, with their common names.

1.Quercus ellipsoidalis x10 Northern Pin Oak  2. Erythrophleum ivorense x10 Missanda
3. Marmaroxylon racemosum x10 Marblewood 4. Caesalpinia libidibia x10 Partridgewood, Coffeewood
5. Cordia trichotoma x10 Peteribi 6. Cercis siliquastrum x10 Judas Tree
7. Quercus dunnii x90 Dunn Oak 8. Quercus ellipsoidalis x10 Northern Pin Oak
9. Quercus ellipsoidalis x90 Northern Pin Oak 10. Bocoa prouacensis x10 Bocoa
11. Calophyllum spp x90 Callophyllum 12. Carya illinoinensis x90 Pecan
13. Chlorophora excelsa x 10 African Teak 14. Fraxinus americana x 10 White Ash
15. Hymenolobium x 10 Hymenolobium 16. Bambusa blumeana x10 Bayog
17. Dalbergia melanoxylon x 10 African Blackwood 18. Couratari spp x 10 Couratari
19. Ceratonia siliqua x 10 Carob Tree 20. Bursera simaruba x 10 Gumbo-limbo, Copperwood
21. Chlorophora excelsa x 10 African Teak 22. Marmaroxylon racemosum x 10 Marblewood
23. Quercus ellipsoidalis x 10 Northern Pin Oak 24.Quercus ellipsoidalis x90 Northern Pin Oak
25. Intsia spp x 10 Intsia 26. Intsia spp x 90 Intsia
27. Jessenia bataua x 10 Pataua, Seje, Milpesos 28. Castanea sativa x 10 Sweet chestnut, Marron
29. Carya illinoiensis x 10 Pecan 30. Carya illinoiensis x 90 Pecan
31. Canarium tonkinense x 10 Chinese White Olive 32. Peltogyne densiflora x 10 Purpleheart
33. Mulettia laurentii x 10 Wenge 34. Mulettia laurentii x 90 Wenge
35. Platymiscium trinitatis x 10 Platymiscium trinitatis 36. Pisonia zapallo x 10 Pisonia zapallo
37. Pisonia zapallo x 90 Pisonia zapallo 38. Dimorphandra hohenkerkii x 10 Dimorphandra hohenkerkii
39. Diplotropis purpurea x 10 Many 40. Eperua falcata x 10 Wallaba
41. Eperua falcata x 90 Wallaba 42. Mullettia laurentii x 10 Wenge
43. Peltogyne densiflora x 10 Purpleheart 44. Pistacia mutica x 10 Mt. Atlas Mastic
45. Pistacia mutica x 90 Mt. Atlas Mastic 46. Rhamnus catharticus x 10 Buckthorn
47. Platymiscium trinitatis x 10 Platymiscium trinitatis 48. Roupala sessilifolia x 10 Roupala sessilifolia
49. Rhamnus catharticus x 10 Buckthorn 50. Pycnanthus angolensis x 10 African nutmeg
51. Sassafras albidum x 10 Sassafras 52. Laburnum anagyroides x 10 Common Laburnum
53. Laburnum anagyroides x 90 Common Laburnum

And here is the video...



Next video is a great hands-on, step-by-step, demonstration of the process by which he prepares the samples. Sample preparation is, like in any artistic endeavor, a key component of the quality of the final product.

 

And finally, is the video in which he demonstrates how the samples are photographed under the microscope. You'll especially appreciate how high-tech the camera and software is, these days, for macrophotography.



Thank you, Mr. Cerre, for this excellent lesson on wood sample macrophotography, for sharing your photographs, and especially for making the effort to include a Google Translate computer voice in your video so that the non-Francais speaking world may enjoy and learn.

1 comment:

Mike Jacobs said...

This presentation fascinated me. Mr. Cerre's fabulous work deserves great praise both for its quality and its contribution to specie identification.

I have a comment regarding the two species photograpthed in the 3rd video: It appeared that the subject matter for close-ups was chosen at random rather than according to consistent parameters. It would seem to me that, in comparing woods, and especially in using Mr. Cerre's database to search for a match to identify an unknown wood, it would be far more helpful to have every close-up taken of the same type of cross-section. For instance, in the 3rd video, the first close-up taken included one open cell of the wood. If each specie's open cells are unique from other species' open cells, a close-up including one of these cells would be a great aid to identification. However, for the second specie photographed in this 3rd video, Mr. Cerre chose a section of the wood for the close-up that showed no open cell, but rather a pitch cell or some other feature.
Perhaps, however, Mr. Cerre is looking for a distinguishing feature unique to each specie, and the area he chose for this close-up perfectly served his purpose?

It will be interesting to see how this system evolves toward positive identification of known species. Will some sort of geometric measurements be taken of various features at a given magnification, or of frequency (or absence) of certain features? Will a computer program be set up with algorithms or other means to read photos for positive ID as is done with fingerprints? And how can we know Mr. Cerre has properly identified each specie in the first place? Will his identification be verified and certified by a body of other wood professionals?

(No criticism here; I greatly value Mr. Cerre's significant contribution toward positive specie identification. These are just some questions that will need consideration in moving toward using his work as the difinitive identification source.)

On a personal note, I find that the intricate and unique design of each wood specie surely points to a Designer.

I could not help but marvel at and thank our Creator, the God of the universe, who has not only done an incredible job in creating over 100,000 unique species of trees, but has also given men the intelligence to invent and use tools to see His work in enough detail to more properly appreciate it and praise Him accordingly.

Mr. Cerre's work gives insight into creation that calls to mind Genesis 1:11-12, wherein it is recorded that, "...God said,'Let the earth sprout vegetation; plants yielding seed, fruit trees on the earth bearing fruit after their kind with seed in them' and it was so. The earth brought forth vegetation, plants yielding seed after their kind, and trees bearing fruit with seed in them, after their kind; and God saw that it was good." On viewing Mr. Cerre's beautiful photos of God's handiwork in creating trees, I believe God was being extremely modest in merely seeing His work as "good"!

"Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and unfathomable His ways! For who has known the mind of the Lord, or who became His counselor? Or who has first given to Him that it might be paid back to him again? For from Him and through Him and to Him are all things. To Him be the glory forever. Amen." -Romans 11:33-36

For a scientific critique clearly showing the world was created rather than evolved, get Thomas L. Hamilton's book, "He Spoke and It was Done", available at Amazon.com.

Mike Jacobs