University of Kentucky College of Agriculture, FOR-136 Food and Environment Cooperative Extension Service

PART IDENTIFYING —A Primer for Everyone 7 Further Distinguishing Softwood Species Terry Conners, Forestry

ecognizing that an unidentified different from each other, and their odors southeastern Canada. It’s sometimes sample is a resinous or non-resinous are very helpful in identifying those spe- known as arborvitae when it is used softwood,R with either an abrupt or a cies. Most species that we casually refer to for an ornamental planting. Some gradual transition, is a good start toward as “cedars” are not true cedars (Cedrela people think the wood has an odor that identifying an unknown specimen. The spp.) and are actually in different genera. resembles the smell of rubber balloons. problem is that this information is rarely Here are a few examples of softwood • Port Orford-cedar ( enough! Other characteristics need to be species that I think have fragrances of lawsoniana) (also known as Lawson’s combined with that data. Some of the diagnostic value: cypress) is a species found in southern things to look out for include character- • Douglas-fir (Pseudotsuga menziesii) Oregon and northern California. The istic odors, the diameter of the tracheids, has an odor that combines a resinous wood has an odor that is described as and the presence of storage cells. Some- smell with a mixture of earthy and spicy or gingery. You might think the times the context or original location of spicy smells. It’s a very distinctive odor. smell resembles Lysol® cleaner. the material can be helpful. • Eastern redcedar ( Juniperus virgin- How to Smell “Cedars” and ), of the cedars, is probably the iana Other Fragrant Species Odors most familiar because of how the wood By the time a wood sample is available The presence of a distinctive odor can is used. You’ll probably recognize the smell from cedar boxes, closet lining, for inspection, the surface may have lost help identify many species, and this ap- much of its characteristic odor, usually plies to both softwoods and hardwoods. or hamster cage litter. This was the preferred wood for pencils up to the because the odor-causing chemicals have Many softwoods have an odor from either evaporated or oxidized into less- resins, oils, and other substances, but early 20th century. As supplies became scarce, incense cedar was substituted. volatile substances. Similarly, samples it’s important to be able to recognize Incense cedar can acquire a surface odor from close, the difference between an odor that • ( decurrens) is the species often used for pencils. It prolonged contact with other is distinctive and an odor that is more or materials. To avoid confusion and to common. The pines are a good example has a characteristic odor (and flavor, for that matter, if you are the type of make the odor more obvious (if it’s actu- of species with noticeable odors, but all ally present), I’ve found that if I cut a thin the pines pretty much smell alike and person who often chews the ends of your pencil). Pencils currently made shaving from the side-grain and barely can’t be distinguished from one another streak the fresh surface with water from by fragrance. (Pines have a resinous smell, outside North America frequently use species from southeastern Asia. the tip of my finger, any naturally oc- particularly on fresh-cut surfaces. I think curring odor seems to revive. Too much of pine as having a sort of resiny-floral Incense cedar was formerly known as Libocedrus decurrens. water will suffocate any odors present, so scent.) Other species, such as the cedars Alaska yellow-cedar be careful not to over-apply it. and Douglas-fir, have distinctive odors • (Callitropsis noot- katensis, formerly Chamaecyparis that set them apart from other species. Texture In most cases, the odor is much stronger nootkatensis), has an odor that I think closely resembles raw white potatoes. Texture has nothing to do with the in the heartwood than in the sapwood; Western redcedar the sapwood odor may be too faint to be • ( plicata) has way the wood feels; it’s the term wood useful as a diagnostic tool. an odor that seems to vary slightly anatomists use when they describe the When you smell the odor on a piece from piece to piece, but it always smells diameter of softwood tracheids. The of wood, it might help to think like a kind of sweet. The odor reminds me tracheid diameters of some species are perfumer: do you smell top notes (very of either bananas or chocolate, or noticeably larger than others, and this volatile, sharp-smelling compounds) or sometimes the two combined. The difference can sometimes help with spe- do you smell bottom notes (more musky odor isn’t always strong, particularly cies identification. Tracheid diameters or earthy)? Think of a description that’s in the sapwood, and it’s stronger when are most easily seen on the cross-section. the wood is slightly damp. Softwood species are described as meaningful to you, because everyone’s Northern white cedar ability to notice scents is a little different. • (Thuja occi- having either a coarse, medium, or fine The woods we call “cedars” smell quite dentalis) is a species that is native to texture, depending on whether the the northeastern United States and

Cooperative Extension Service | Agriculture and Natural Resources | Family and Consumer Sciences | 4-H Youth Development | Community and Economic Development Figure 7-1. Baldcypress ( distichum), a coarse-textured Figure 7-2. Eastern white pine (Pinus strobus), a medium-textured species. It’s easy to spot individual tracheids with a 10X lens, and species. With a 10X lens, you can see that the surface is covered you can almost believe that you can trace the outlines of indi- with tracheids, but it’s practically impossible to distinguish any vidual cells. individual cell. tracheid diameters are large, medium, for comparisons, or very small, respectively. With a good- but they are all re- quality 10X hand lens, you might try to produced at the categorize the wood this way: if you can same magnifica- easily see the tracheids on the cross-sec- tion. Note that tion, and if they almost look large enough the tracheids are for you to trace the circumference of much easier to see one with your eye, then you are looking in the coarse-tex- at a piece of wood with a coarse texture tured baldcypress (ex., redwood or baldcypress). If you can compared to the easily see tracheids on the end grain but eastern white pine, you can’t distinguish one tracheid from and the tracheids another, then you are looking at a sample aren’t visible at all with medium texture (ex., eastern white in the eastern red- pine). Fine-textured woods have even cedar. smaller tracheid diameters; a dry cut Texture can be might actually appear a bit shiny to the helpful in wood naked eye (ex., eastern redcedar); using identification; just a 10X hand lens as before, you would be by looking at the unlikely to be able to distinguish cellular texture with a structure of any kind were it not for a bit hand lens, for ex- Figure 7-3. Eastern redcedar (), a fine-textured of torn grain or a bit of knife chatter here ample, an analyst species. Even with a 10X lens, it’s impossible to distinguish any and there. can distinguish individual tracheids on this cross-section, and in fact you may not Here are some cross-section micro- between anatomi- be able to distinguish any cells at all. graphs to illustrate the differences in cally similar spe- tracheid dimensions (identical magnifi- cies such as the coarse-textured sugar (P. strobus) or western white pine (P. cations). These micrographs (Figure 7-1 pine (P. lambertiana) and a medium- monticola). Other common species with through 7-3) are significantly enlarged textured pine such as eastern white pine fairly coarse tracheids include hemlock, Douglas-fir, and the southern pines.

2 Parenchyma Parenchyma cells (pronounced par- EN-ki-muh) are thin-walled cells that are used for storage. Most parenchyma run longitudinally in the wood (parallel with the tracheids), though some paren- Band of chyma are oriented perpendicular to the parenchyma tracheid axis and form much of the ray tissue (“ray parenchyma,” of which more will be said later). Longitudinal paren- chyma are often filled with food (starch) or other waste products, and these are often colored. Colored parenchyma are Growth ring easy to see on the cross-section, and they can provide another clue to the identifica- tion of an unknown sample. If the surrounding wood is light- colored, softwood parenchyma might be visible as individual colored dots or band-like groups. You will need to examine a cleanly cut cross-section to have any chance of finding parenchyma Figure 7-4. A photograph of eastern redcedar (Juniperus virginiana) I made from a Hough with a hand lens, but they may not be veneer. I lit the veneer from the backside to show the parenchyma cells more clearly. No- visible unless a thin shaving is backlit for tice the thin bands of parenchyma and how they blend into the latewood. In the marked growth ring example, the parenchyma bands look discontinuous. The dark reddish-brown viewing. (Looking for parenchyma with a coloration indicates the irregularly shaped heartwood in this sample. microscope may be easier than searching for them with a hand lens in many cases.) Figure 7-4 shows a photograph of eastern redcedar to illustrate dark-colored paren- chyma cells. You sometimes have to look carefully to figure out if you are looking at growth rings or parenchyma. In Figure 7-4 the parenchyma form tangential bands, but individual pa- renchyma cells might also be scattered throughout the growth ring. Other com- mon examples of softwoods with colored parenchyma cells include baldcypress, redwood, and some of the other so-called cedars. The photograph of a baldcypress ve- neer (Figure 7-5, below) shows numerous bands of colored parenchyma that can be seen fairly easily even with the naked eye. These bands are different from false growth rings (which are also found in this species). In this sample I distinguished the parenchyma from false growth rings by looking at it under a stereoscope with backlighting; the parenchyma were filled with dark material and visibly discon- tinuous in the tangential direction. False latewood tracheids don’t have colored contents, and they are continuous tan- gentially (also refer to the micrograph of Figure 7-5. Photograph of baldcypress cross-section with numerous parenchyma cells, baldcypress in Figure 7-1). most of which are banded in this example. Arrows point to several (but not all) of the groups of parenchyma.

3 Summary Vocabulary Softwoods can be either resinous or non-resinous, and the growth ring transi- If you don’t remember any of the fol- tions can be either gradual or abrupt; in lowing words, please review this sec- most cases, more information is needed tion. Vocabulary is very important! 1. Texture: coarse, medium, fine to identify an unknown sample, however. 2. Parenchyma: ray parenchyma and Odor can be very helpful for some spe- longitudinal parenchyma cies. Texture (a term used in reference to 3. Pinus strobus (eastern white pine) tracheid diameter) can be distinguished 4. Pinus monticola (western white with a 10X lens, and it can also be helpful pine) 5. Pinus lambertiana (sugar pine) in separating wood species. Longitudinal 6. Picea (the genus name for the parenchyma, thin-walled storage cells, spruces) run parallel with the tracheids and fre- 7. Pseudotsuga menziesii (Douglas-fir) quently have colored contents that make 8. Juniperus virginiana (eastern red- them easy to see on a magnified cross- cedar) 9. (western redcedar) section. The presence of parenchyma is 10. (northern white notable in some species and can assist cedar) in determining the identification of an 11. Callitropsis nootkatensis, formerly unknown sample. Parenchyma are also Chamaecyparis nootkatensis (Alaska located in rays. yellow-cedar) 12. (baldcypress) 13. (Port Orford-cedar) 14. formerly known as Libocedrus decurrens

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