A Laboratory Manual

A LABORATORY MANUAL

FOR FP 4013/6013

WOOD ANATOMY

H. M. Barnes, Professor Department of Forest Products College of Forest Resources MISSISSIPPI STATE UNIVERSITY © August 2004

0 TABLE OF CONTENTS

Table of Contents...... 1

Species ...... 2

Textbooks, Equipment, Items of Interest...... 3

Exercise 1 ...... 4

Exercise 2 ...... 7

Exercise 3 ...... 9

Exercise 4 ...... 10

Exercise 5 ...... 11

Exercise 6 ...... 12

Exercise 7 ...... 14

Exercise 8 ...... 15

Exercise 9 ...... 16

Exercise 10...... 17

Exercise 11...... 18

What's Possible With Wood Identification? ...... 19

Wood Identification Keys For Hand Lenses ...... 28

SPECIES (fill in blanks) Block # Common name Scientific name Family Softwoods (Gymnosperms) 1 Eastern white pine Pinus strobus 2 Red pine 3 Southern pine Pinus palustris spp. 4 Ponderosa pine Pinus ponderosa 5 Eastern spruce Picea spp. Sitka spruce Picea sitchensis 6 Western larch 7 Douglas-fir Pseudotsuga menziesii 8 Eastern hemlock Tsuga canadensis 9 Redwood Sequoia sempervirens 10 Baldcypress Taxoidium distichum 11 True fir Abies spp 12 Alaska-cedar 12a Northern white-cedar Chamaecyparis occidentalis 13 Incense-cedar Calocedrus decurrens 14 Western redcedar Thuja plicata 15 Eastern redcedar Juniperus virginiana 16 Atlantic white-cedar Chamaecyparis thyoides 17 Port-Orford-cedar 18 Pacific yew Taxus brevifolia Hardwoods (Angiosperms) 19 Red oak Quercus rubra spp. 20 White oak Quercus alba spp. 21 Ash Fraxinus americana, F. (White, green, Oregon) pennsylvanica, F. latifolia 22 Sassafras Sassafras albidum 23 Honeylocust 24 American elm Ulmus americana 24a Slippery elm Ulmus rubra 25 Hard elm Ulmus alata, U. crassifolia, U. thomasii 26 Osage-orange Maclura pomifera 27 Black locust 28 Red mulberry Morus rubra 29 Hackberry Celtis occidentalis spp. 30 Blackgum Nyssa sylvatica 31 Black cherry Prunus serotina 32 Black walnut Juglans nigra 32a Butternut Juglans cinerea 33 Willow Salix nigra 34 Persimmon Diospyros virginia 35 Hickory Carya spp. 36 Cottonwood Populus deltoides 37 American beech 38 Sycamore, American planetree Platanus occidentalis 39 Hard maple (sugar, black maple) Acer saccharum, A. nigrum

2 40 Soft maple (red, silver maple) Acer rubum, A. saccharinum 41 Yellow-poplar Liriodendron tulipifera 42 Basswood Tilia americana 43 Sweetgum, redgum Liquidambar styraciflua* 44 Birch Betula spp. 45 Red alder Alnus rubra 46 Dogwood Cornus florida 47 Aspen Populus tremuloides 48 Magnolia Magnolia grandiflora 49 Chestnut 50 Pecan Carya illinoensis

A. Textbooks: Textbook of Wood Technology, 4th Edition; Identifying Wood

NOTE: This laboratory manual will be needed during each laboratory session. You MUST have the laboratory manual, laboratory notebook, and textbooks every lab period!

B. Equipment: (1) Utility knife (2) Single edge razor blades (3) Hand lens (MUST be 10-16X) (4) Good quality, small paint brush (5) Tweezers and probe (6) Small ruler/straight edge (7) A bound lab notebook

C. Items of interest

(1) Drawing is required for the laboratory exercises, but exams may also require artistic ability - be prepared.

(2) All underlined subject matter in the laboratory manual will require instructor approval upon completion. Data from your laboratory manuals should be put into your lab notebooks and will be checked periodically.

(3) There will be a short QUIZ during most laboratory sessions covering material from the previous exercises.

(4) Assignments will NOT be accepted late.

3 EXERCISE 1

MICROSCOPE CALIBRATION AND PRINCIPAL WOOD PLANES

Objectives: To become familiar with the operation of your microscope; to determine the operating parameters of your microscope; to become familiar with the principal planes of a block of wood.

A. MICROSCOPE CALIBRATION

1. Magnification. Magnification of an objective lens depends upon the working distance of the objective and the tube length of a microscope. The working distance of the objective lens (focal length of objective lens) is the distance between the objectives lens and the object when the microscope is in focus. For practical purposes, the magnification of an objective lens may be obtained from the formula:

objective lens magnification = microscope tube length objective lens focal length

Your microscope is equipped with objective lenses having working distance of 4, 8 and 16 millimeters. The common tube length of most microscopes is 160 millimeters.

Determine the objective lens magnification for your microscope.

a. lower power = ______

b. medium power = ______

c. high power = ______

Within limits, the magnification of a microscope is the product of the eyepiece magnification time the magnification of the objective.

Determine the magnification of your microscope.

a. lower power = ______

b. medium power = ______

c. high power = ______

2. Calibration of ocular micrometer. The calibration of a microscope is essentially the comparison of an unknown scale (ocular micrometer) with a known scale (stage micrometer). To do this, proceed as follows:

(1) Using the medium power objective (8mm), focus on the stage micrometer scale. The eyepiece micrometer should also be in focus and should appear superimposed on the stage micrometer scale.

(2) Line up the zero mark on the stage micrometer with the zero mark on the ocular micrometer.

(3) Observe the point at which one of the scale divisions (y) on the ocular micrometer coincides with a scale division on the stage micrometer (x).

(4) Count the number of divisions on the ocular micrometer between the coincident lines.

(5) Count the number of divisions on the stage micrometer between the coincident lines and convert to microns. The smallest division is equal to 10 microns.

(6) Find the value of one division on the ocular micrometer by dividing the number of divisions into the number of microns between coincident lines on the stage micrometer.

Example: Ocular micrometer = 47 divisions Stage micrometer = 75 divisions or 10 x 75 = 750 microns

Microns / ocular division = No. of microns stage micrometer No. of divisions ocular micrometer

= 750/47 = 15.95 microns

(7) Repeat the procedure for your objectives and record below.

a. low power = ______

b. medium power = ______

c. high power = ______

B. PRINCIPAL WOOD PLANES

1. Locate the principal surfaces on your white pine blocks.

(a) Cross or transverse section (b) Radial section

5 (c) Tangential section

Sketch in your notebooks a three (3) dimensional view of your white pine block and label its principal planes, annual rings (alternating springwood and summerwood zones) resin canals, etc.

2. Practice making razor blade sections of your pine block and study them under your microscope. Prepare sections of each of the three surfaces, and identify major anatomical structures.

a. Cross section ______b. Radial section ______c. Tangential section ______

BE SURE TO COMPLETE LABORATORY WORKSHEET #2 IN YOUR NOTEBOOKS

6 EXERCISE 2

WOOD TEXTURE & GROSS ANATOMICAL FEATURES

Objective: To determine what dictates, and become familiar with, various wood textures; to introduce some basic physical and anatomical properties useful in wood identification

Texture in wood is determined by the size of individual wood elements. Wood with small diameter cells is referred to as fine textured. Wood with large diameter cells give a different appearance and is called course textured.

1. From a slide of southern pine or eastern red cedar, measure and record the following for a springwood and summerwood tracheid.

Species = ______Springwood Summerwood

a. Tangential cell diameter = ______

b. Radial cell diameter = ______

c. Tangential cell wall thickness = ______

d. Radial cell wall thickness = ______

2. Repeat (1) for a tracheid of redwood or bald cypress.

Species = ______Springwood Summerwood

a. Tangential cell diameter = ______

b. Radial cell diameter = ______

c. Tangential cell wall thickness = ______

d. Radial cell wall thickness = ______

3. Measure the length and diameter of several tracheids of some macerated softwood. Calculate the average length and diameter.

Species______

Length Diameter (1) ______

(2) ______

(3) ______

(4) ______

(5) ______

Total = ______Total =______

Avg = ______Avg = ______

4. Determine by visual observation the relative texture of the following woods (fine, medium, coarse): Texture

a. redwood ______

b. western hemlock ______

c. eastern red cedar ______

d. baldcypress ______

e. southern yellow pine ______

5. Work through Laboratory Worksheet #3 and put in your notebooks.

8 EXERCISE 3

MICROSCOPIC STUDY OF SOFTWOODS

Objective: Learn to identify various minute features of gymnosperms.

A. Locate and identify the following (draw each in your notebook):

1. Transition a. Gradual White Pine (x) b. Abrupt Southern Pine (x)

2. Pitting of Longitudinal Tracheids (Ray Crossing) (Text P & dZ pg. 109). a. Fenestriform White Pine (r) b. Pinoid Southern Pine (r) c. Piciform Douglas-fir (r) d. Taxodioid Redwood (r) e. Cupressoid Eastern Red Cedar (r)

3. Spiral Thickenings Douglas-fir (r)

4. Intercellular spaces Eastern Red Cedar (x)

5. Rays a. Uniseriate White Pine (t) b. Biseriate Redwood (t) c. Non-dentate ray tracheids White Pine (r) d. Dentate ray tracheids Southern Pine (r)

6. Longitudinal Parenchyma a. Marginal Hemlock (x) b. Diffuse Redwood (x) c. Strand Bald Cypress (r or t)

B. Locate and identify the following pit structures (draw in your notebooks):

1. Simple pits Species______location______

2. Bordered pit-pairs Species______location______

C. Be sure to answer Laboratory Worksheet #4 in your notebooks.

9 EXERCISE 4

IDENTIFICATION OF SOFTWOODS I

Objective: Identification of softwoods having resin canals.

Learn to identify the following softwoods.

(1) Sugar Pine

(2) White Pine

(3) Ponderosa pine

(4) Lodgepole pine

(5) Southern pine

(6) Red pine (how can red pine be separated from southern pine?)

Complete Laboratory Worksheet #5 in your notebooks(add the following as question 3a: Southern pine and red pine are very difficult to separate; what is the major microscopic feature separating the two species; draw this difference in your notebooks)

(7) Spruce

(8) Sitka spruce

(9) Douglas-fir

(10) Western larch

Complete Laboratory Worksheet #6 in your notebooks

10 EXERCISE 5

IDENTIFICATION OF SOFTWOODS II

Objective: Identification of softwoods normally not having resin canals.

Learn to identify the following softwoods:

(1) Baldcypress (red cypress, yellow cypress, southern cypress)

(2) Hemlock

(3) True fir

(4) Redwood

(5) Pacific yew

Complete Laboratory Worksheet #7 in your notebooks

(6) Alaska-cedar (yellow cypress)

(7) Port-Orford cedar

(8) Northern white-cedar (eastern arborvitae)

(8) Incense-cedar (pencil cedar)

(9) Atlantic white-cedar (southern white-cedar)

(10) Western redcedar (giant arborvitae)

(11) Eastern redcedar

Complete Laboratory Worksheet #8 in your notebooks

11 EXERCISE 6

MICROSCOPIC STUDY OF HARDWOODS

Objectives: Learn to identify various minute features of angiosperms

Locate and identify the following: (x = cross section; r = radial; t =Tangential; l = r or t)

1. General Topography (Low magnification)

a. Ring Porous Red Oak (x)

b. Diffuse Porous Sweetgum (x)

c. Semi-ring Black Walnut (x)

2. Vessel Arrangement (Low magnification)

a. Solitary Yellow Poplar (x) b. Radial Rows Holly (x) c. Wavy Tangential Bands Elm (x) d. Nests Black Locust (x)

3. Spirals in Vessels Black Cherry (r)

4. Perforation Plates

a. Simple Red Oak (r)-macerated b. Scalariform Sweetgum (r)

5. Tyloses (may need to cut razor blade section) White Oak (x-l)

6. Vessel Pitting

a. Opposite Yellow Poplar (t) b. Alternate Sycamore or Red Oak (t) c. Scalariform Magnolia (t)

7. Rays

a. Multiseriate Sycamore (t) b. Homocellular Sycamore (r) c. Heterocellular Sweetgum (r)

12 8. Tracheids

a. Vasicentric Red Oak (r) b. Vascular Elm (r) c. Sepate Fiber Tracheids Mahogany (r or t)

9. Longitudinal Parenchyma

a. Maringal Yellow Poplar (x) b. Apotracheal Diffuse Sweetgum (x) c. Paratracheal Vasiocentric Persimmon (x)

C. Locate and identify the following pit structures:

1. Simple pits

Species______location______

2. Bordered pit-pairs

Species______location______

Complete Laboratory Worksheet #9 in your notebooks

13 EXERCISE 7

IDENTIFICATION OF HARDWOODS I

Objective: Identification of ring porous hardwoods.

Learn to identify the following hardwoods:

1. Red oak

1. White oak

3. American elm

4. Hard elm

5. Slippery elm

6. Hackberry

Complete Laboratory Worksheet #10 in your notebooks

14 EXERCISE 8

IDENTIFICATION OF HARDWOODS II

Objective: Identification of ring, semi-ring porous hardwoods.

Learn to identify the following hardwoods:

1. White ash

2. Sassafras

3. Red mulberry

4. Honey locust

5. Osage-orange

6. Black locust

7. Hickory

8. Pecan

9. Black walnut

10. Common persimmon

Complete Laboratory Worksheet #11 in your notebooks

15 EXERCISE 9

IDENTIFICATION OF HARDWOODS III

Objective: Identification of diffuse porous hardwoods.

Learn to identify the following hardwoods:

1. Red alder

2. Yellow-poplar

3. Hard maple

4. Blackgum

5. Cottonwood

6. Aspen

7. Black cherry

Complete Laboratory Worksheet #12 in your notebooks

1. American sycamore

2. American beech

3. Yellow birch and paper birch

4. Magnolia

5. Sweetgum

6. Holly

7. Soft maple

8. Basswood

9. Dogwood

10. Willow

Complete Laboratory Worksheet #13 in your notebooks

16 EXERCISE 10

MACERATED TISSUE EVALUATION

Objectives: To become familiar with specific anatomical wood structures.

A. Prepare a slide of macerated southern pipe. Locate and identify: (Tracheid)

1. Intertracheid pits- bordered pits of pit pairs leading to a contiguous longitudinal tracheid.

2. Ray-tracheid pits- small bordered pits of pit pairs leading to a ray tracheid.

3. Ray-parenchyma pits- large varishaped pinoid pits of pit pairs leading to ray parenchyma.

B. Repeat (A) using Douglas-fir. Locate and identify: (Tracheid)

1. Ray-tracheid pits 2. Ray-parenchyma pits 3. Intertracheid pits 4. Spiral thickening

C. Repeat (A) using white oak. Locate and identify:

1. Vasicentric tracheid (showing ray-contact area) 2. Springwood vessel element (showing ray-contact area and tyloses) 3. Summerwood vessel element (showing simple perforation plate). 4. Parenchyma cells (showing pitting)

D. Repeat (A) using Sweetgum. Locate and identify: (vessel)

1. Spiral thickening in the ligulate tip 2. Scalariform perforation plate 3. Ray contact area 4. Fiber contact area

17 EXERCISE 11

CROSS SECTION OF A YOUNG STEM

Objectives: (1) Learn to prepare temporary slides for microscopic study; (2) To become familiar with the principal structures of woody stems.

2. Prepare a fresh cross section of a young gymnosperm stem, and identify the following:

a. resin ducts e. primary phloem

b. pith f. secondary phloem

c. primary xylem g. cambial zones

d. secondary xylem

2. Repeat (1) for an angiosperm.

a. resin ducts e. primary phloem

b. pith f. secondary phloem

c. primary xylem g. cambial zones

d. secondary xylem

18 What's Possible With Wood Identification Terry Conners, Department of Forestry, University of Kentucky (updated 7/03)

Introduction:

You lose details/information with every step you take away from the plant. Some elements of gross and/or microscopic structure are common to a number of related species. For example, red oak is a commercial name for a group of oaks for which the woods cannot be distinguished. However, given the bark, acorns, and leaves, the species which compose this group can be identified. The same thing goes for the southern pines. Given just the wood, loblolly pine cannot be distinguished from shortleaf pine, longleaf pine, etc.

Trees: bark, leaves, buds, twig and branch form, PLUS the wood characteristics

Wood: color(s), odor, taste, hardness, size, sheen, other physical characteristics (such as splintery or not, presence of "dimples" or not, "pith fleck" or not, etc.), presence of heartwood, plus the microstructure (inter-relationships among fibers and rays, ray tissues and structures (ray heights and widths, special cell types present such as dentate ray tracheids), growth ring structure (ring-porous, semi ring porous, or diffuse porous), presence or absence of special structures (resin canals)), PLUS the pulp characteristics

Pulp: lengths, diameter, cell wall thicknesses, pit structures and arrangement, types of cells present and relative percentages, vessel element appearance (spiral thickenings, pitting, perforation plates)

Sawdust and Finer Materials: These can be very tough to analyze, but you can usually get some useable information if you're willing to be patient. Microscopic information is chancy, but often you can find some little bit here or there that might suggest one species or another, or at least one (fairly large) group of woods. Sometimes a chemical test is helpful; a fairly simple test can distinguish between hardwoods and softwoods, for example, but there are no other tests I'm aware of to tell you that something is red oak or red pine, for example. Elemental composition tests (ex., energy-dispersive x-ray spectroscopy) are hardly ever useful for wood, as most woods have similar elemental composition. Some do have higher amounts of certain elements like calcium, but these species are not the common ones you are likely to encounter. Examples of such woods include red mulberry and teak, but you must keep in mind that considerable natural variation occurs with all species; a calcium or other mineral content which is somewhat high is not necessarily of diagnostic significance for a given wood.

Charcoal: Most charcoal samples are very fragile and require embedding in a low-viscosity epoxy-type resin before sectioning (with a glass or diamond knife in an ultramicrotome), but the anatomical features required for identification are often preserved to a great extent.

Paper: Paper can be a complex product to analyze, as there are often several species present in any given paper. Some of these species may have been manufactured by different processes (such as mechanical grinding, sulfate ("kraft process") or sulfite). Recycled fibers may be present

19 as well, and this might mean, for example, that traces of certain west-coast species could be present in a paper manufactured on the east coast. Recycled fiber content is determined by inference from species mixtures or pulping types, but it cannot be absolutely distinguished by any objective laboratory means known. Market pulps are pulps sold by mills with excess pulping capacity, and it may be difficult to know when these are present unless unusual geographic/species combinations are present. Market pulp use is fairly common even on an international scale; for example, in the mid 1980s Procter and Gamble ceased purchasing aspen from the area surrounding its Green Bay, Wisconsin facility and supplanted it with eucalyptus pulp from Brazil shipped in through the St. Lawrence Seaway. Recycled fibers are also sold as market pulps. For forensic analysis of a paper sample I would look at the chemical composition of the paper (ash and presence or absence of fluorescent dyes)), presence or absence and type/design of watermarks, the paper thickness and other mechanical properties if the sample is large enough to be testable by a contract lab, and the fiber content (species and species percentage breakdown and type of pulp present (groundwood, sulfate, sulfite: determined using Graff's "C" stain)). The ash composition and percent ash may be useful because various papers have different coating and filler compositions and amounts. Still, there can be enough similarity among papers made by different manufacturers that, coupled with normal production variation, often the best you can do is to state that a given sample is consistent with the sample it is compared to.

What kind of facilities do I need to do wood or fiber identification?

I try to do as much of my work as possible with just a 10X/15X combination hand lens, but that isn't always enough. When I do need to check something with a microscope, an ordinary light microscope with 4X, 10X and 40X objectives is all that is normally needed, although I confess though that on occasions I have resorted to a 100X oil immersion lens. I generally prefer a light microscope to a scanning electron microscope - it's faster and I can see multiple layers in a sample that isn't quite thin enough. Along with this, I use an X-Acto retractable razor knife (orange plastic utility knife with #8R replacement blades – without the breakaway tips), some industrial single-edged razor blades like you might buy at the hardware store for cutting wallpaper, and a water bottle. Depending on the sample, I might also use a small saw to obtain a small piece from a larger sample, and I might make thinner sections (about 20-40 μm) from the smaller piece in a sliding microtome with a steel knife. A little Congo red or methylene blue stain is sometimes useful, along with fast green and safranin-O, plus Graff's "C" stain (but this last is iodine-based and has a limited shelf life). (Obviously, slides and cover slips are needed as well.)

If I have a big piece of wood to identify, can I tell anything more from that piece than I could from a small piece of the same wood?

Probably not, unless the small piece of wood is unusually small. I've done lots of wood identifications from very small pieces of wood, sometimes little more than a splinter. It's helpful to remember that wood cells are generally pretty small in diameter - often only about 20 to 40

20 μm - so there are lots of cells to look at even in a small piece. The challenge is to take that piece and examine it. It's pretty easy with a large piece of wood, because you can use a microtome to make lots of nice clean sections. With a small piece a little more finesse or understanding of what you're looking for is required.

What basic information do I need to get started?

Well, wood identification is sort of like peeling an onion - you can just keep on going deeper and deeper. To get started, though, let's discuss a couple of basic concepts.

1) Wood is an orthotropic material. In other words, it has three planes of view which are mutually perpendicular, and the appearance of the wood looks different on each of these three planes. If you've ever had a histology course, our use of these three planes as standard reference planes will simplify matters considerably. Each plane is assigned a name corresponding to a geometrical view. If we consider a tree to be similar to a cylindrical rod, then that rod has a) a radial dimension and an infinite number of individual radii; b) an infinite number of tangents perpendicular to the major (i.e., longitudinal) axis of the cylinder; and c) a cross-section. In wood, the cross-section corresponds to the view of the stump when you cut down a tree, exposing the annual growth rings. The tangential surface corresponds to the surface(s) at right angles to the radii, just beneath and parallel to the bark, and the radial surface corresponds to the surfaces which are exposed along the radial axes of the stem. Here's a sketch:

Cross-section:

Longitudinal Axis

Most of the cells in wood are arranged with their long axes parallel to the longitudinal direction (fibers and vessels), but there are also some tissues composed of very short cells arranged in the radial direction ("rays"), extending from the pith in the center to the bark.

2) Hardwood anatomy is distinctly different from softwood anatomy. Softwoods are generally considered to be anatomically simpler, for one thing. For another, softwoods lack a type of cell which is of diagnostic significance for hardwoods - the "vessel element". Vessel elements stack one on top of another to run continuously from the ground to the crown (forming "vessels"), and serve as the major conduction path for fluids in a tree. They can often be seen on a cleanly-cut cross-section of a piece of wood with the naked eye, and hence are sometimes called "pores"; hardwoods are sometimes known as "porous woods". The size and arrangement

21 of these vessels as seen on a cross-section is useful in determining the species of wood you are looking at.

3) "Hardwoods" are not necessarily harder than "softwoods". The common terms "hardwood" and "softwood" are often substituted for the botanically correct "angiosperms" and "gymnosperms", but they do not refer to the actual hardness of the wood. For example, balsa is a well-known "hardwood", but is actually quite soft and can be dented with a thumbnail quite easily. On the other hand, southern pine, a well-known "softwood" can be so hard that carpenters bend nails when framing with this wood.

4) The appearance of the cross-section and the growth rings is helpful. Growth rings are the annual rings of woody tissue added to the tree by the cambium each year. Growth rings are usually composed of two types of tissue visible on the cross-section, the earlywood (or springwood) which is added during the beginning of the growing season, and the latewood (or summerwood) which grows during the second part of the growing season. Earlywood and latewood usually look different (because the cell structure is somehow different), and that is why we can count how old a tree is when we look at a tree stump cut close to the ground. The earlywood is often less dense and (in softwoods) lighter in color than the latewood. In softwoods the density and color differences are caused by differences in cell wall thickness, as earlywood has thinner cell walls than does the latewood. The change between thin and thick cell walls causes a color change which can be observed with the naked eye or a hand lens, and the rapidity with which this change is made is of diagnostic significance when used in combination with the presence or absence of other features. A "gradual transition" may be typical of an eastern white pine, for example, while an "abrupt transition" is typical of a southern yellow pine.

Earlywood Cross-section of a Softwood Growth Ring Latewood (Abrupt Transition)

In some hardwoods there are lots of large pores visible in the earlywood, while the latewood looks as though there are only a few pores of a much diminished size. This is called a "ring- porous" wood. There are some very familiar woods with this structure, such as oaks, ash and hickory. Other hardwoods have vessel elements of about the same size scattered uniformly across the growth ring. These woods are termed "diffuse-porous". Examples of these woods include: birch, maple, beech, and aspen. Because these latter woods have no clearly visible earlywood-latewood zones, it can sometimes be difficult to distinguish individual growth rings. Some species have a thin band of (often colored or pale white) storage cells called parenchyma cells at the boundaries of the growth rings. Due to their location at the edges of the growth rings,

22 these cells are often called marginal parenchyma. The presence of marginal parenchyma is useful in identifying certain diffuse-porous woods such as basswood.

Hardwood Ring-Porous Hardwood Diffuse-Porous Growth Ring Growth Ring

5) Chemical and physical properties are often helpful in larger samples. All woods have approximately the same basic chemical composition, but there is a class of chemicals called "extractives" which is responsible for the differences in color, odor and taste. Extractives can be removed from wood using neutral solvents such as hot or cold water, alcohols, acetone, and benzene, and their removal will not affect the cellular structure of the sample. Extractives can vary tremendously from species to species; they make black walnut heartwood a warm chocolate brown, and they also make Osage-orange (bois d'arc) wood a bright orange-yellow. Extractives are not always colored, but when they are colored they often are more readily seen in the heartwood of a tree (if heartwood is present). Sapwood (the part of a tree which is just beneath the bark, generally light-colored) contains the same extractives as the heartwood, but the concentration is much lower. If you are identifying a wood specimen based on the gross features, therefore, extractive characteristics will be most useful to you when heartwood is present.

To this point I have emphasized that color is attributable to extractives as this is a characteristic with which we are all probably somewhat familiar, but I only made mention of odor and taste. These can actually be invaluable in identifying certain types of wood such as cedars. You are probably familiar with the pleasant tang of a pencil (incense cedar) and the odor of a cedar chest (eastern redcedar). Other cedars, however, can smell like cheap balloons or even potatoes. Douglas-fir also has a distinctive odor and taste, and some hardwoods smell like oregano or kerosene. These tastes and smells can be of diagnostic significance even in the absence of other features - at least for certain species.

Other than looking for extractives (color, taste and odor), you should try to determine whether other physical characteristics (ex., hardness and density) are consistent with your tentative identification.

23 How do I actually go about trying to identify a piece of wood?

You probably already have a piece of wood in mind - I hope that you don't want to start with a splinter! It's a good idea to get used to looking at wood anatomy in more manageable sizes from various angles (and off-angles) before you attempt to tackle anything which might get particularly challenging. For the moment, let's stick to learning how to identify wood using just the gross features - those you can taste, smell or see with your eyes or a 10–15X hand lens. The basic procedure is quite skeletal:

1. Look at the piece of wood for your first impressions. "Grok" it. Some woods speak to you right away (although some lie!), and you merely have to confirm a suspected identity. For other woods, you might have to key them out using either an expert system or a dichotomous key. If you want to check for odor, note that woods often tend to lose the odor from the top-most surface layers (and the color might also have oxidized to a muddier-brown color than when it was freshly cut). Make a thin cut to expose a fresh surface, and perhaps lightly dampen the revealed wood. Too much water does two things: a) it cuts down the noticeable odor, and 2) it fills in the cells, obscuring details. Only "soak" the wood if you know that you need to carve away at it pretty heavily. Always remember: You may not have seen this species before, so you shouldn't work too hard to fit a specimen into your technical vocabulary if it looks unfamiliar.

2. If you have to key out the wood, or if you want to run the wood through a formal identification confirmation, you next have to slice the wood such that the three principal planes (cross-section, radial and tangential) are accurately exposed. A little water usually helps to soften the wood for a sharp razor blade or some such. I don't recommend using X-Acto knives other than the utility knife with #8R blades due to tapered blades, etc., nor do I care for utility knives or pocket knives. The real problem with these last knives is that they force your hand to be un- parallel with the surface you are trying to create, with the result that you often take thicker sections than you need to along a greater surface area, with less accuracy. Frankly, this is the one part of the job where beginners often have problems. Both for safety and for the sake of a good clean cut, try to cut only as much surface area as you need to. This might be an area only about one-half that of a common pencil-tip eraser!

3. To make a cut: Wet the wood slightly if you haven't done so already. Tap water is fine, but a little saliva works well too. Grip the block of wood in your non-cutting hand. Hold that block like an ice cream cone, with your hand wrapped all the way around it. Brace your hand by placing your forearm against your lower ribcage. Next, grip your razor knife in a four-fingered fist, and place the block of wood between the knife edge and your thumb, keeping your thumb well below the anticipated plane of your cut!!! (Unless you own stock in your local hospital or bandage manufacturer.) Carve away. Try to make your cuts parallel with the plane you're trying to reveal or clean up; beginners often cut the cross-section at a forty-five degree angle, for example, and are perplexed by the unusual perspectives presented.

If you are using a single-edged razor blade, the procedure is much the same except that you have no thumb to use as a brace on your cutting hand. This can create belly nicks if you get carried away and the blade slips, so I encourage you to be careful and, again, to take small cuts. You are less likely to be struggling and applying dangerous pressures on a blade which is only trying to

24 remove a small section of wood. Don't be afraid to change the blade if the edge gets turned. A blade might last for twenty sections in a soft wood, while a harder species like oak might turn the edge of the blade after only a couple of uses. As much as I am loath to recommend using razor blades, I must admit that they have no equal for hand-sectioning, which is a useful skill to acquire for fast microscopy work.

After you've congratulated yourself on making a good cut on one surface, go ahead and make cuts on the other two planes! You'll find that it's hardest to make a smooth cut on the cross-section. Often it works best when you cut in the tangential direction - your knife doesn't chatter going through sequences of low density material (earlywood), then high density material (latewood), then low density material, etc.

4. Look at the exposed surfaces. Examine the wood for color and odor, and determine whether you are holding a hardwood or a softwood. You will find the hand lens useful here. From this point on it helps to know a bit more anatomy. Here are some of the more important things to know.

Softwood Anatomy: I already mentioned that softwoods have a pretty simple anatomy compared to hardwoods. In fact, most softwoods are composed entirely of fibers (more correctly known as longitudinal tracheids) and rays in a ratio of about 90:10. Some softwoods, though, also have a structure known as a resin canal. This is merely a small hole in the wood, a little bigger than a longitudinal tracheid, which accumulates resin ("pitch") from some of the surrounding cells. Only four types of trees found in North America normally have resin canals: the pines, spruces, larch (also known as tamarack) and Douglas-fir. Resin canals are usually large and plentiful in the pines, but smaller and sparser in the other species. Species identifications of softwoods are usually possible with a hand lens based on color, odor, hardness, type of earlywood-latewood transition (gradual or abrupt), and the presence/absence, size and abundance of resin canals.

Sometimes it is useful to be able to describe one other additional feature: the texture of the wood. This does not refer to the wood's feel, but instead refers to the typical cross-sectional diameter of an individual longitudinal tracheid. A piece of wood with a coarse texture has fairly large tracheids (ex., southern pine and Douglas-fir), while a piece of wood with a fine texture has very small diameter tracheids. Medium texture wood is intermediate between the two. In coarse- textured woods, individual tracheids can be almost (but not quite) distinguished with a hand lens, while for medium-textured woods the best you can do is notice that the cross-section has lots of very small holes. Fine-textured woods do not appear to have holes on the cross-section at all unless a microscope is used.

25 Hardwood Anatomy: Hardwood structure can be complex, but it is the variety of cell types present and the way in which they can be arranged that makes hardwood identification somewhat easier than softwoods for the knowledgeable person. As noted above, hardwoods can have the vessel elements arranged in either a diffuse-porous or ring-porous fashion, classified according to the change in size and distribution (if any) between the earlywood and latewood. A few woods have an arrangement which is somewhat intermediate (for example, a very small, more or less contiguous initial row of earlywood pores, followed by pores throughout the remainder of the growth ring which are slightly diminished in size and frequency). These woods are known as either semi-ring porous or semi-diffuse porous; the terms are synonymous. An example is black cherry. Sometimes the latewood vessels are arranged in patterns (like undulating sine waves), and these woods are said to have a figured latewood; elms are good examples here.

Some hardwoods have balloon-like growths called tyloses which are present in the vessel elements of some species. The presence or absence of tyloses can be important, and can even be of diagnostic significance for some species. White oaks generally have tyloses, for example, while red oaks lack them or have them in small quantities.

Unlike softwoods, hardwoods have many cell types. Under a visual or hand lens inspection, however, only a few of these are apparent. These cell types include: hardwood fibers (known as fiber tracheids), vessel elements, rays and those storage cells (parenchyma cells) referred to earlier in the discussion about locating softwood growth ring boundaries. The fibers have no diagnostic significance and the importance of distinguishing the vessel element arrangement has already been referred to, but the rays and parenchyma cells can also be seen easily and may provide valuable information about the sample under investigation.

Rays: Rays are not of much importance to softwood identification with a hand lens because they all pretty much look alike, but ray appearance is more variable in hardwoods. We are interested in seeing how big the typical ray is - both in terms of its height along the grain and its width in the tangential direction. Some woods have rays that are only one cell wide in the tangential direction (hence essentially invisible unless a microscope is used), others have rays which are 30 or more cells wide and which can be easily seen with the naked eye; the oaks are a good example of a species with these broad rays. Often rays are colored slightly differently from the rest of the wood, and this makes them easier to see. Rays can be seen on all three surfaces: the cross- section, the radial plane and the tangential plane. They look like continuous spokes on the cross- section, for example, but on the tangential plane they will look like very short fine pencil lines. Species like maple will have rays which are only about 1mm high, while red oaks will have rays about 1/4-1/2" high, and white oaks will have rays 1/2-1-1/4" high (typically) or higher. On the radial plane, rays have a characteristic "ray fleck" pattern which resembles a ribbon. If the plane of cut is a true radial surface, and if the ray proceeds straight from the pith to the bark, a continuous ribbon is seen; more than likely, however, one condition or the other will not be perfectly met and the plane of the section will pass through each ray seen. This will result in the radial plane exhibiting a number of discontinuous ribbons.

Parenchyma Cells: Parenchyma cells are notable because they can be a significant part of a hardwood's volume - as much as 40%. They usually appear somewhat whitish, and they often appear in certain patterns which can be distinctive. Sometimes parenchyma appear in thin lines

26 which parallel the growth rings (called "banded parenchyma"); sometimes when parenchyma are present they always surround the vessel elements. The presence and location of parenchyma can be of diagnostic significance. For example, a true hickory has banded parenchyma only in the latewood; if banded parenchyma also appear between the large earlywood vessel elements, the wood is a pecan hickory species. As another example, the presence of banded parenchyma can also be used to separate hickory from ash, another ring-porous wood with which it is sometimes confused. Ash has parenchyma which surround each vessel element (as can be seen with a 10X lens) and does not have banded parenchyma. Hickories do not have parenchyma associated with the vessel elements. See paratracheal parenchyma and apotracheal parenchyma in the vocabulary list at the end of this handout.

I work in forensics as a trace analyst, and my specimens are typically very tiny. I don't think that a hand lens is going to do the job. What sort of approach do you recommend?

You're probably right - for small pieces a hand lens isn't going to be very effective. You basically have three choices: 1) use a magnifier to make small slivers (if necessary) for light microscope identification of anatomical features and key the sample out; 2) use a scanning electron microscope for the same purpose, or 3) macerate the sample in a caustic solution to separate the cells for microscopic examination and identification. This order pretty much follows my own preferences and prejudices. Regardless of the method used, sample identification will require knowledge of the types of cells found in rays, certain features of softwood longitudinal tracheids, and an intimate acquaintance with the features of hardwood vessel elements (as these last look different for every species and are of diagnostic significance in their own right). I usually prefer light microscopy because I can turn the sample over and around and I can stain for added contrast. Transmitted light also reveals details of cell structure which are not at the immediate surface. SEM is limited in that regard, and there is the added inconvenience of the metallic coating which must be applied to eliminate charging artifacts. If SEM is used, I would recommend using as low an accelerating voltage as your instrument is capable of with adequate imaging. Using an accelerating voltage less than 1 keV might mean that you don't need to coat the sample in a newer SEM; in an older SEM without the very low voltage capability I would advise using no more than 15 keV

Maceration is really the last resort, as small cells are probably going to be lost and their relationship to each other will be destroyed. Species identifications are still possible - after all, it's the same type of analysis that can be conducted with paper - but more care and judgement are required. Also, there is the possibility that the sample will be over-cooked and that the sample will dissolve! Please exercise caution and proceed with room-temperature reactions whenever possible. This might mean that the maceration proceeds in three days instead of 20–90 minutes, but conducting the maceration at room temperature will let you observe the progress of the maceration and exercise more control over the reaction.

27 Wood Identification Keys For Hand Lenses

By Terry Conners Forest Products Extension Specialist Department of Forestry University of Kentucky Lexington, KY 40546-0073 (859) 257-2463

Note: In this key, T, R, and X indicate that a feature will be seen on the tangential, radial, or cross-section surface respectively.

Resinous Softwoods

Resin Canals Abundant, Evenly Distributed Resin Canals Sparse, Unevenly Distributed

Gradual Transition Abrupt Transition Gradual Abrupt Transition Transition

Medium Coarse Often has Often has a Often has a Resin canals Resin canals texture texture broad, well- narrow narrow band very small, small, visible defined band of of latewood appearing as as dark spots latewood latewood (semi-abrupt white dots or openings, (fast-grown) to abrupt often in transition) tangential bands

On the Heavy, hard Moderately Moderately Earlywood Characteristic average, the light, heavy, zone usually odor on freshly resin canals moderately moderately much wider cut surface are slightly soft soft than the smaller than latewood those of sugar pine

Yellow- Lustrous Yellowish to brown orange red

Frequently No dimples Growth rings dimpled on often wavy a split (esp. in old tangential growth) surface

Crates, Crates, Pulpwood, Crates, Pulpwood, Pulpwood, Construction, millwork, millwork plywood, moldings, construction construction, plywood, furniture construction furniture musical pulpwood instruments

White pine Sugar Southern Ponderosa Red pine Spruce Douglas-fir pine pine pine

Separate these two woods These two woods are by texture sometimes confused with spruce because the growth rings can look similar at first glance. Pay attention to the resin canals.

Non-Resinous Softwoods (except cedars)

Gradual Transition Gradual to Abrupt Transition Abrupt Transition

Creamy white to pale Light brown with pinkish Color ranges from Heartwood is brown hue yellow to light or dark characteristic light red to brown, sometimes deep reddish brown on reddish or almost black fresh surface, sapwood is white

Latewood often has a Latewood looks brown Abrupt transition is Narrow lines of distinct lavender tinge common latewood

Sometimes has a salty Feels "dry" to touch, Old-growth wood is dark No odor taste more brittle and splintery colored, has a "slick" than fir feel, and may have a rancid odor. Newer Cross-section cuts Cross-section is difficult growth wood is smoothly to cut yellowish and lacks the "slick" feel and rancid odor

Thin cross-section is not Thin cross-section is dry False and/or Coarse texture crumbly and crumbly discontinuous growth rings common; growth rings look variable in width

Pulpwood Construction, pulpwood Old-growth material is Construction used where decay resistance is important

Balsam fir Hemlock Baldcypress Redwood

These two woods are often confused.

Cedars (Non-resinous softwoods)

Heartwood has a distinct odor

Pinkish brown Reddish brown Bright yellow Uniform straw- Yellowish- Purplish or to dull brown to dull brown heartwood brown white to pale rose-red heartwood heartwood yellowish heartwood, brown often with inclusions of white sapwood

Sweetish odor, Pencil odor Odor resembles Balloon-like Spicy odor, like Familiar cedar often faint, raw potatoes odor ginger or Lysol chest odor sometimes compared to bananas or chocolate

More or less Gradual Inconspicuous abrupt transition growth rings, transition especially when dry

Moderately Medium texture Fine texture Fine texture Medium texture Fine texture coarse texture

Dark bands of Growth rings Some latewood Dark bands of parenchyma very narrow bands may parenchyma often visible show up as visible, near the ends of orange streaks especially in the growth ring on longitudinal sapwood (Cross-section) surfaces

Shingles, poles Pencils Poles, stadium Poles, shingles, Millwork Fence posts, seats log cabins chests, novelties

Western Incense cedar Alaska cedar Northern Port-Orford Eastern redcedar white cedar cedar redcedar

Sometimes Sometimes confused with confused with redwood redwood (color) or because of incense cedar color. Watch (odor and odor and color) texture.

Ring-Porous Woods, Coarse Texture

Broad rays No Broad Rays (Rays indistinct without hand lens)

Distinct Latewood Latewood pores solitary, or in nested groups Latewood latewood pores pores not pores in radial distinct groups or flame-like Few tyloses Many tyloses Pores in latewood solitary, Interrupted pattern frequently joined laterally by concentric paratracheal parenchyma bands of latewood pores at end of the latewood

Rays (T) 1/4- Rays (T) up to Whitish Dull brown Gray brown Gray brown to 1/2" long 12" - 2" long color color brown (type. 2 -13")

No odor Distinctive Characteristic Often wormy - spicy odor and odor sometimes BUT NOT taste (bologna similar to RELIABLY or oregano) kerosene SO !!!

Very hard Wide, variable growth rings

Narrow rays

Same uses as Railroad ties, Handles, Misc. local Fence posts, Formerly white oak, but cooperage, furniture, uses, number of old-time cure important for used more veneer, baseball bats, logs sold as for intestinal large timbers, frequently for flooring, mine veneer "black ash" worms furniture, fence furniture. Not timbers, some posts, tannin used for tight furniture source cooperage.

Red Oak White Oak White Ash Sassafras Catalpa American Chestnut

Ring-Porous Woods, Coarse Texture

Figured Latewood Unbigoted Latewood Single row Several rows of earlywood pores of earlywood Earlywood pores filled Earlywood pores not pores with tyloses completely filled with tyloses

Earlywood Orange to Golden Orange- Whitish gray Reddish- pores yellow brown, may yellow to with gray or brown distinct have a red-brown, black streaks; greenish turning often has a tinge dark brown distinct on exposure yellowish tinge.

Wood hard Wood hard Hard and heavy and heavy

Latewood Earlywood Earlywood Latewood Latewood pores Pores in pores in pores pores more pores in in continuous nest-like wavy fuzzily individually interrupted wavy bands groups in tangential defined distinct wavy bands (similar to elm) outer bands latewood ("ulmiform pores")

Light brown Yellow Yellow White No calcium heartwood coloring is coloring calcium deposits water- much less deposits in soluble water- earlywood soluble pores

Abundant Fewer tyloses tyloses

Bent Fence Fence Fence Furniture, Fence posts, furniture, posts, posts, rail posts, millwork furniture cooperage bows and mine caskets timbers

American Osage Black Red Hackberry Kentucky Elm Orange locust Mulberry Coffeetree (Bois d'Arc)

Red elm has Sometimes Color like two to four confused with Honeylocust rows of Elm, but the but H. locust large rays are much has reddish earlywood more readily gum deposits vessels; visible to the in vessels - Hard Elm eye. Elm is not none in KY has v. small yellowish. Coffeetree EW pores.

Ring Porous Semi-Ring Porous (Semi-Diffuse Porous)

No Broad Rays Rays Not Distinct to Naked Eye Rays Distinct to Naked Eye

Brown-red Brown-red Yellow- Light brown Light brown Red-brown heartwood heartwood, gray-brown to dark with streaks heartwood, sometimes has chocolate whitish darker streaks brown sapwood heartwood, whitish sapwood

Hard, heavy Hard, heavy Hard, heavy Hard Soft

Numerous bands of Numerous bands of Indistinct apotracheal bands of parenchyma, Parenchyma parenchyma (in apotracheal appearing as closely spaced lines (net-like) not visible latewood only), parenchyma between the rays arranged irregardless throughout the of vessel element growth ring position (Apotracheal)

Latewood pores Ripple Characteristic No The first row solitary marks odor; thin characteristic of earlywood visible on rays odor; Thin pores is the rays somewhat tangential larger than surface the rest and is in a more or less continuous uniseriate row (pores fairly small)

Handles, ladders, Furniture, veneer Turned Finest cabinet Furniture, furniture, furniture wood wood - veneer veneer products, furniture, golf club veneer, heads gunstocks

Hickory Pecan Hickory Persimmon Black Butternut Black Walnut (White Cherry Walnut)

Sometimes confused More gradual with White Ash, but transition than true White Ash lacks the hickory; Pecan has banded parenchyma apotracheal banded parenchyma in EW.

Semi-Ring Porous to Diffuse Porous

Rays Indistinct Even With a 10X Hand lens

Pale creamy white to light grayish Dull white to light grayish brown Light brown to reddish brown, brown often streaked

Pores not visible without hand lens Largest pores barely visible to the Largest pores barely visible to the naked eye naked eye

Marginal parenchyma usually not Light-colored marginal Marginal parenchyma usually not visible parenchyma more or less distinct visible

Growth rings distinct because of Growth rings distinct but Growth rings inconspicuous darker latewood, wide inconspicuous, narrow to very wide

Characteristic, disagreeable odor Characteristic, disagreeable odor No characteristic odor or taste when moist when moist

Silky luster No silky luster

Pulp, wooden matches Pallets, pulp, excelsior Boxes, crates, carvings, novelties

Aspen Cottonwood Willow

Aspen and cottonwood are often confused; pay attention to the pore size.

Diffuse Porous (Pores Indistinct w/o Hand lens)

Broad Rays Plainly Visible to the Naked Eye, Much Wider Than the Rays Distinct to the Naked Eye, But Largest Pores Not Broad

Broad and Narrow Rays Visible With Uniform Width Rays Hand lens

Light brown with Whitish with a Whitish to a reddish Uniform light White to light reddish tinge reddish tinge to brown reddish brown; brown, reddish brown infrequent pith sometimes with flecks; sometimes a gray-green or birds-eye figure purplish tinge; pith flecks fairly common

Moderately soft and Hard and heavy Moderately hard and Hard, heavy Moderately hard light heavy and heavy

Broad rays are Broad rays are Broad rays are Rays of two widths, Rays vary irregularly and often much more uniformly distributed on the widest about as slightly in width widely spaced, uniformly the cross-section wide as the largest (but more sometimes absent distributed on pores uniform than from small cross- the cross- Hard Maple), sections section the widest about as wide as the largest pores

Broad rays about 1" Broad rays Broad rays appear as Rays very close Growth rings high (T); very thin appear as short, closely packed (but short) on the delineated by a narrow rays relatively lines (Tangential face) tangential face narrow darker widely spaced, band, not staggered lines sharply defined (Tangential)

Ray flecks widely Ray flecks Ray flecks are very Ray flecks are very Rays form a spaced (Radial face) closer (Radial close (Radial face) close (Radial face) conspicuous face) fleck (Radial)

Furniture, pulp Women's shoe Furniture, millwork Furniture, floors, Furniture soles, handles, flooring, charcoal clothespins

Red Alder Beech Sycamore Hard Maple Soft Maple

Hard vs. Soft Maple: 1) color 2) ray width 3) pith flecks

Diffuse Porous

Rays Distinct to Naked Eye Rays Inconspicuous

Two ray sizes: broad rays Rays mostly Rays numerous and crowded Rays separated and fewer visible to the naked eye and of one size narrow rays scarcely visible even with a hand lens

Light pinkish White Wide white Wide, Whitish with Creamy white Pale yellow brown sapwood, sapwood, whitish a pinkish to pale brown; to reddish sapwood to ivory-white heartwood sapwood, tinge, often light and soft brown; dark brown heartwood; variable from sometimes blue-stained, moderately heartwood; hard, heavy light brown to with dark often with hard and hard, heavy green-brown, streaks darker heavy Small pores sometimes (gray streaks of in radial purple to heartwood) pigment clusters black markings; light and soft

Growth rings Growth Marginal Growth rings not distinct Marginal Growth not as rings barely parenchyma parenchyma rings distinct as distinct common common indistinct Hard Maple

Indistinct Indistinct Light-colored Often has interlocked grain, Characteristic Pith flecks banded diffuse ray fleck hard to split odor (old common on apotracheal parenchyma often visible wood slide white birch parenchyma (R) boxes)

Shuttles Inlays, Veneer, Boxes, Veneer Veneer for Furniture, scrollwork, furniture, pallets concealed turnings,, stained to pallets furniture parts toothpicks, match popsicle ebony sticks

Dogwood Holly Yellow- Blackgum Redgum Basswood Birch poplar (Tulip (Tupelo) (Sweetgum) poplar)

Dogwood vs. Separate these on the basis Birch vs. Hard Maple: of color Maples: 1) Dogwood Compare denser; 2) pore size to color; 3) ray width apotracheal on the banded cross- parenchyma section in Dogwood

37 Definitions of Terms Applicable to the Identification of Wood

Extracted, with additions and amendments by T. Conners, from The Textbook of Wood Technology, 4th edition, by Panshin and de Zeeuw, published by McGraw-Hill.

Aggregate Ray: Composite structure, consisting of a number of small rays, fibers and sometimes also vessels, which to the unaided eye or at low magnification appears as a single broad ray.

Aliform Parenchyma: Type of paratracheal parenchyma that extends out from the flanks of a pore, forming an eyelet with it; "Wing-like" shape.

Annual Ring (Growth Ring): Annual increment of wood as it appears on a transverse surface or in a transverse section

Apotracheal-diffuse Parenchyma: Single apotracheal parenchyma strands or cells distributed irregularly among fibers, as seen in cross-section

Apotracheal-diffuse-in-aggregate Parenchyma: Apotracheal parenchyma cells that tend to be grouped in short tangential lines from ray to ray, as seen in cross-section

Apotracheal Parenchyma: Axial parenchyma independent of the vessels (pores); includes marginal, diffuse, diffuse-in-aggregate, and banded parenchyma.

Axial Parenchyma: Parenchyma cells derived from fusiform cambial initials; also known as longitudinal parenchyma.

Banded Parenchyma: Axial parenchyma forming concentric lines or bands as seen in cross- section; termed apotracheal banded parenchyma if independent of the pores and paratracheal banded parenchyma if definitely associated with the pores.

Cross-grain: In standing trees, "grain" where the fiber alignment deviates from the axis of the stem; in wooden members, grain in which the fiber alignment deviates from the direction parallel to the long axis of the piece. See also Spiral Grain.

Cross-section: Section cut at right angles to the fiber axis; top of the tree stump. Same as Transverse section.

Curly grain: Grain that results from more or less abrupt and repeated right and left deviations from the vertical in fiber alignment; the radial split faces of such wood are corrugated, the split tangential faces are smooth or corrugated.

Diffuse parenchyma: Apotracheal parenchyma the cells of which are scattered in the growth ring.

38 Diffuse-porous wood: Porous wood ("Hardwood") in which the cross-sections of vessel elements ("pores") exhibit little or no variation in size indicative of seasonal growth. See Ring-porous wood.

Early Wood: That portion of a growth increment which is produced at the beginning of the growing season; also known as Springwood. See Latewood.

Epithelium: Excreting parenchymatous tissue surrounding the cavity of resin and gum canals.

Extractives: Chemicals which can be removed by solvents from wood without changing its cellular structure. Examples of typical solvents include: Hot water, Cold water, Ethanol, Ethanol/Benzene, etc. Extractives are frequently colored materials and are of some diagnostic importance since they generally cause the characteristic coloring associated with various species, especially in the heartwood. Not all extractives are colored; some cause a wood's characteristic odor, smell or taste.

False Ring (False Growth Ring): Band of what appears to be latewood followed outwardly by tissue resembling earlywood, which is in turn followed by true latewood, wholly included within the boundaries of a single season's growth.

Fusiform Ray: Softwood ray which contains a radially-oriented resin canal.

Grain of wood: Arrangement and direction of alignment of wood elements when considered en masse.

Hardwood: Wood produced by broad-leaved trees such as oak, elm, maple, birch, etc. Same as porous wood (contains vessel elements).

Heartwood: Dead inner core of a wood stem or log, generally (but not always) distinguishable from the outer portion (sapwood) by its darker color. See Sapwood.

Interlocked grain: A condition produced in wood by the alternating orientation of fibers in successive layers of growth increments. The quarter-sawn face of such wood (the Radial plane) produces the appearance of a ribbon figure.

Latewood: That portion of an annual increment (growth ring) which is produced in the latter part of a growing season, during the summer; Summerwood. See Earlywood.

Longitudinal Resin Canal: Resin canal parallel to the wood fibers, appearing as an opening or fleck on the cross-section with the naked eye or hand lens. Small/light-colored in spruce, small/dark in Douglas-fir, generally large in pines.

Marginal Apotracheal Parenchyma: Apotracheal parenchyma, the cells of which occur singly or form a more-or-less continuous layer of variable width at the close of a season's growth, in which case it may also be called Terminal Parenchyma (or at the beginning of a season's growth, when

39 it may also be called Initial Parenchyma). Generally, the term Initial Parenchyma is seldom used, and for most practical purposes the terms Marginal and Terminal Parenchyma may be used synonymously.

Mineral Stain: Olive and greenish-black streaks believed to designate areas of abnormal concentration of mineral matter; common in hard maple, hickory and basswood. Also called Mineral Streak.

Nested Pores: On the cross-section, the appearance of several pores which appear to be contained in a nest-like grouping, occasionally coalescing. Diagnostic feature of Gymnocladus dioicus (Kentucky Coffeetree).

Nonporous wood: Wood devoid of vessel elements (pores). Same as "Softwood" or coniferous wood.

Paratracheal Confluent Parenchyma: Coalescent aliform parenchyma forming irregular tangential or diagonal bands as seen in cross-section.

Paratracheal Parenchyma: Parenchyma, the cells of which are obviously associated with the vessels (pores); not a random kind of association.

Paratracheal Vasicentric Parenchyma: Paratracheal parenchyma forming a complete sheath around a vessel element (as seen in cross-section).

Parenchyma: Tissue consisting if short, relatively thin-walled cells, generally with simple pits; concerned primarily with storage and distribution of carbohydrates; used specifically as a synonym for axial parenchyma which occurs in strands along the grain; may be visible with a hand lens on the transverse surface as dots, as sheaths around pores, or as broken or continuous lines or bands.

Pecky dry rot: Characterized by finger-sized pockets of decay in living trees of incense-cedar and baldcypress.

Pit: Common term for a pair of openings breaching the cell walls (except for the cell membrane) of two adjacent cells.

Pore Chain: Several to many vessels (pores) arranged in a radial line or series (Cross-section), the adjacent vessels retaining their separate identities. See Pore Multiples and Nested Pores.

Pore Multiple: Group of two or more vessels contiguous in the radial direction as seen on the cross-section; flattened along the lines of contact so as to appear as subdivisions of a single pore.

Porous Wood: Wood containing "pores" (vessels); same as "Hardwoods", i.e., wood produced by broad-leaved trees.

40 Prosenchyma: Generally obsolete term, botanically; still used by wood scientists to refer to non- parenchymatous tissues, i.e., those cells whose functions are mainly conductive and mechanical, generally equipped with bordered pits. See Parenchyma.

Radial Section: Section cut along the grain parallel to the wood rays and at right angles to the cross-section, perpendicular to the growth rings. See also Tangential Section.

Ray: Ribbon-shaped strand of tissue extending in a radial direction across the grain, so oriented that the face of the ribbon is exposed as a "fleck" on the radial, or quarter, surface; the cross- section of the ray is exposed on the tangential surface, beneath the bark, but is only visible in those species such as oaks that have rays with non-trivial width and height.

Ray Fleck: Portion of a ray as it appears in side view on the radial surface.

Ray Height: Number of ray cells across a ray's major axis (in the longitudinal direction), as measured on the Tangential surface.

Ray Width: The number of cells across a ray's minor axis, as measured either on a Cross-Section or on a Tangential surface.

Resin Canal: Tubular intercellular space sheathed by secreting cells (epithelium), bearing resin in the sapwood of some species. In North America, the genera with normal resin canals are: Pinus, Picea, Pseudotsuga, and Larix (Pines, spruces, Douglas-fir and Larch).

Ring-Porous Wood: Wood containing vessels ("pores") in which the vessels formed at the beginning of the growing season (in the earlywood) are much larger and more frequent than those formed in the latter portion of the growing season (latewood). The transition from one type of vessel size and distribution to another is more or less abrupt.

Ripple marks: Striations across the grain on the tangential face of a piece of wood, caused by storied rays or by these and other storied elements.

Sapwood: Outer (younger) portion of a woody stem (or a log), usually distinguishable from the core (heartwood) by its lighter color. See Heartwood.

Semi-Diffuse Porous Wood: Wood intermediate between diffuse- porous and ring-porous wood. See Semi-Ring Porous Wood.

Semi-Ring Porous Wood: Synonymous with Semi-Diffuse Porous Wood.

Softwood: Wood produced by coniferous trees; same as nonporous wood.

Spiral Grain: Grain in which the fibers are aligned in a helical orientation around the axis of the stem.

41 Storied Rays: Rays arranged in tiers or in echelons as viewed on a Tangential surface or in a tangential section under the microscope. See Ripple Marks.

Straight Grain: Wood in which the direction of the fiber alignment is straight; also refers to the grain orientation in standing trees which is parallel to the stem axis.

Tangential Section: Section cut parallel with the fiber axis and at right angles to both the Radial and the Transverse sections.

Texture of Wood: Expression that refers to the Size and Proportional Amounts of wood elements. In Softwoods, Texture refers to the average tangential diameter of the tracheids, with large-diameter tracheids being referred to as "Coarse Texture" and small-diameter tracheids being referred to as "Fine Texture". In Hardwoods, texture refers to the tangential diameters and numbers of vessels and rays.

Tracheids: Most commonly, a "Fiber" in coniferous trees. It is a fibrous lignified cell with bordered pits and imperforate ends. In coniferous wood, the tracheids are very long (up to 7+ mm) and have large prominent bordered pits on the radial walls. In Hardwoods, tracheids are shorter fibrous cells (seldom over 1.5 mm long), are as long as the vessel elements with which they are associated, and possess small bordered pits. In hardwoods, "tracheid" generally is used to refer to a cell more properly known as a Fiber Tracheid. (Hardwoods also contain Vascular and Vasicentric Tracheids).

Transition: In Softwoods, termed "Gradual Transition" or "Abrupt Transition"; this refers to the rate of change in the typical growth ring between Earlywood and Latewood. This transition is readily seen by the change from the light-colored Earlywood to the more dense, darker-colored Latewood. In Hardwoods, the transition is marked by the change in the size and frequency of the vessel element distribution, and is named accordingly; see Ring-Porous, Diffuse-Porous and Semi-Ring Porous.

Transverse Resin Canal: Resin canal extending across the grain, included in a Fusiform Ray.

Traumatic Resin Canal: Resin canal supposedly arising as a result of injury.

Tylosis (pl. Tyloses): Sac-like or cyst-like structures that sometimes develop in a vessel and rarely in a fiber through the proliferation of the protoplast (living contents) of a parenchyma cell through an opening in a cell wall called a Pit. More common in certain species than others and often used as a diagnostic feature, although some caution must be used when exercising this feature as the sole diagnostic (esp. in Oaks).

Vessel / Vessel Element: A Vessel is an articulated, tube-like structure of indeterminate length in hardwoods, composed of individual cells called Vessel Elements. The ends of these Vessel Elements are perforated in several patterns which have some diagnostic significance in microscopic identification.

42 Sources of Information and Materials :

Terrance E. Conners (Terry) Associate Professor Department of Forestry 202 Thomas Poe Cooper Building University of Kentucky Lexington, KY 40546-0073

859/257-2463 Voice 859/619-9018 Cell 859/323-1031 Fax [email protected] e-mail address

Source for microscope slides of authentic samples:

Carolina Biological 2700 York Road Burlington, NC 27215 800/334-5551

Textbooks and Other Reference Materials:

Papermaking Fibers (Various authors, depending on edition) Charles H. Carpenter, Lawrence Leney, Harold A. Core, Wilfred A. Côté, Jr., and Arnold C. Day in my 1963 edition. (It's been updated since) State University of New York at Syracuse, Technical Publication No. 74

Identification of North American Commercial Pulpwoods and Pulp Fibres I. Strelis and R.W. Kennedy University of Toronto Press in association with the Pulp and Paper Institute of Canada Copyright 1967 (Out of print)

Pulp and Paper Microscopy Good for pulp stain information Irving H. Isenberg The Institute of Paper Chemistry, Appleton, Wisconsin Third Edition, 1967 (Note: The Institute of Paper Chemistry moved to Atlanta, Georgia in 1989 and renamed itself The Institute of Paper Science and Technology. As of July 2003 it is part of Georgia Tech. This book has long been out of print.)

Sources for Fiber Analysis (Paper Samples):

Integrated Paper Services John D. Hankey and Associates 101 West Edison Avenue, Suite 250 119 North Douglas (Zip code 54911) P.O. Box 446 P.O. Box 1856 (Zip code 54913) Appleton, WI 54912-0446 Appleton, Wisconsin 414/749-3040 Voice 414/734-8511 414/749-3046 Fax

44 The Mäule Test

This test can be used to discriminate between samples containing hardwood lignins and softwood lignins.

Page 230, Methods of Wood Chemistry by B.L. Browning, Interscience Publishers, 1967

The test is based on chlorination followed by addition of sodium sulfite. Phenolic compounds containing the 1,2,3-trihydroxy benzene nucleus produce a red color. Hardwood lignins and some tannins produce characteristic colors with this test. The hydroxyl groups can be partially substituted, but at least one hydroxyl group must be free.

The response of some compounds to the test is as follows: guaiacol and veratrole, none; vanillin, reddish brown; eugenol, weak color; syringic acid, strongly positive; gallic acid, strongly positive; 1,2,3-trimethoxy benzene, weak. ------Pages 277-278, Methods of Wood Chemistry by B.L. Browning, Interscience Publishers, 1967

Mäule in 1900 observed a characteristic color reaction of lignified tissues that has since come to be known as the Mäule test. The tissue is treated with a 1% solution of potassium permanganate for a few minutes, washed, treated with 12% hydrochloric acid, again washed, and then moistened with ammonium hydroxide. An intense purple-red color is produced with deciduous woods and a brown shade with coniferous woods.

. . .

A positive Mäule test is found only for those wood which give syringaldehyde in addition to vanillin upon nitrobenzene oxidation. Towers and Gibbs (Nature 172(25) [1953]) found that the syringaldehyde-vanillin ratios obtained on nitrobenzene oxidation of plant materials roughly paralleled the intensity of the Mäule test. Thus, the test serves as a reliable means of differentiating woods from gymnosperms and angiosperms.

------

W.E. Spearin and R.C. Dressler (Tappi 37(1):39-42, 1954) used 1% potassium permanganate, a wash, 6N hydrochloric acid, a wash, then a solution consisting of 1 part of concentrated ammonium hydroxide to 5 of water.