GYMNOSPERM WOOD IDENTIFICATION A component of MIAMI UNIVERSITY DENDROLOGY EXPERT SYSTEM CREATED BY DR. ROGER D. MEICENHEIMER

Very distinct boundary between thinner cell walls of spring wood tracheids and thicker cell walls of summer wood tracheids within one annual growth ring. Gradual change in cell wall thickness between spring and summer wood tracheids within one annual growth ring. Single pit at any given horizontal level along a tracheid. Two or more complete pits occupy a given horizontal level along a tracheid in the opposite arrangement. Strap-like extensions radiate from the torus in radial view. Individual pit borders appear flattened or notched instead of circular in radial view. Periodic regions of thicker cell wall material, normally inclined at ca. 90 degrees to longitudinal axis of tracheid. Don't confuse with checking artifact oriented at 10-45 degrees. Axial parenchyma can be observed in transverse, radial, and tangential sections. Do not include parenchyma associated with resin canals or wound healing in this character. Assess the density of axial parenchyma in the transverse section of region in the wood that contains it. Most often axial parenchyma occurs in spring wood. Abundant simple pit pairs give the short end walls of axial parenchyma a nodular or beaded appearance as viewed in tangential longitudinal section. Large square or rectangular pits with little or no apparent borders. One to three pits nearly fill the cross field. Large square or elliptical pits with slight to obvious borders. At least some of the cross fields have more than three pits per field. Pits nearly fill the cross field. Widest part of pit aperture is about equal to diameter of pit chamber. Narrowest part of pit aperture is about equal to border width in the center of the pit. Widest part of pit aperture less than diameter of pit chamber. Narrowest part of pit aperture less than width of pit border in the center of pit. Extremely small pits with narrowly elliptical apertures. Widest part of aperture extends slightly beyond pit chamber. Narrowest part of aperture less 1/3 size of the border at center. Thin horizontal walls of ray parenchyma are thinner than vertical walls of adjacent axial tracheids as viewed in radial section. Horizontal walls of ray parenchyma lack simple pits as viewed in radial section. Simple pits are abundant in horizontal walls of ray parenchyma as viewed in radial section. Abundant simple pits in end walls of ray parenchyma give them a nodular appearance in radial section. Corners of ray parenchyma are thicker than edges of the same cell as viewed in tangential section. Wood has more than two rays per mm that are higher than 30 cells as viewed in tangential section. Cuboidal, octahedral, or rectangular crystals can be present in ray cells. Use of polarizing microscopy can help in locating these crystals. No obvious uneveness in cell walls. Very small projections of cell wallmaterial extend into lumen of ray tracheids. Obvious tooth-like projections of cell wall material into lumens of ray tracheids. Numerous cell wall projections form an interconnected network within the lumens of ray tracheids. Resin ducts running vertically within wood can be most easily observed end-on in transverse section, but can also be seen occasionally in longitudinal sections. Resin ducts running horizontally within the rays can be most easily seen in tangential section, but can be occasionally observed in transverse and radial longitudinal section as well. Thin epithelial cell walls are thinner than the cell walls of axial tracheids. Thick epithelial cell walls are similar in thickness to the cell walls of axial tracheids. Count the number of epithelial cell walls associated with resin ducts as viewed in tangential section. For accuracy in counting, make sure all epithelial cells are intact. Count the number of epithelial cells lining the horizontal resin ducts as viewed in tangential section. For accuracy in counting make sure all epithelial cells are intact. Wood has a uniform appearance. Wood exhibits variation in appearance. Less than 30 pounds per cubic foot 31 to 40 pounds per cubic foot 41 to 50 pounds per cubic foot Greater than 50 pounds per cubic foot Less than 25 pounds per cubic foot 26 to 30 pounds per cubic foot 31 to 34 pounds per cubic foot Greater than 35 pounds per cubic foot Less than 400 pounds 400 to 499 pounds 500 to 599 pounds 600 to 699 pounds Greater than 700 pounds Makes you pull away or wrinkle your nose. Wood smelling this way should be examined for freshness since some wood decaying bacteria/fungi produce disagreeable odors & are nondiagnostic! Resembles "Pine Trees". Caused by volatile compounds associated with liquid resins in canals - so look for resin canals. Resembles "Pencils" or " Cedar Chests" Caused by volatile compounds sequestered in individual cells and cell walls - so look for presence of axial parenchyma. Wood has some odor to it that you may or may not associate with something. Be sure that what you are smelling is associated with the wood, rather than decay organisms. Assess using a light microscope to examine transverse (X), radial (R), and tangential (T) sections of wood. Assess relative cell wall thickness of tracheids in spring (early) and summer (late) wood in transverse (X) section. Axial tracheids are elongate parallel to stem axis. Assess the details of pit features and variations in cell wall thickness within axial tracheids viewed in radial section. Axial parenchyma cells are vertically elongated cells that contain cytoplasm, have simple pits, and appear rectangular in radial and tangential longitudinal section. Rays run radially within the stem and are typically lighter than surrounding axial tracheids. Assess cell types and pit details in radial sections containing complete rays. Assess the number and shape of cross field pits, or pits occurring between individual axial tracheids and individual ray parenchyma cells. Use radial sections of spring wood. Ray parenchyma contain cytoplasm, have simple pits, and are rectangularly elongated in the radial plane. Assess details of cell walls and presence of cystals. Ray tracheids occur along the margins of rays, have circular bordered pits, slanted end walls, and no cytoplasm. Assess details of cell wall thickening. Well defined canals or ducts that are lined with parenchymatous epithelial cells. Assess orientation of ducts; number and cell wall thickness of epithelial cells. Assess these characters visually with the unaided eye, and by using the feel, smell, and taste of FRESH wood. Many of these characteristics are best learned through comparative experience. Caveat: Many of the Macroscopic Characters pertain to FRESH samples! Wood (FRESH or OTHERWISE) is most reliably identified using microscopic features, given the extreme variations present in wood macroscopic characteristics and human perception of these variations! Distinct rays are visible with the unaided eye. Rays extend radially from center toward the outside and are typically lighter than the surrounding wood. Use transverse or tangential plane Visually assess the uniformity of wood appearance. Produced by relative arrangement of different cells and/or color in the wood. Sometimes confused with grain (orientation of tracheids). Assess by touch. Reflects size and distribution of various cells in the wood. Relative weight of green wood. Reflects Sap/Heart and Spring/Summer Wood Ratios and Moisture Content. Increasing moisture increases weight. Weigh and measure your sample, then calculate the weight per cubic foot. Relative weight of kiln dry wood. Reflects Sap/Heart and Spring/Summer Wood Ratios and Moisture Content. Increasing moisture increases weight. Weigh and measure your sample, then calculate the weight per cubic foot. Assess by pressing surface with fingernail. Closely related to weight, but increasing moisture decreases hardness. Varies in transverse, radial, and tangential surfaces. Tilt radial surface of split wood to reflect light. Luster is proportional to size and density of ray and axial parenchyma in general. Care should be used if examining planed or sanded wood Pertains to Sapwood (younger, usually lighter, peripheral region of stem). Reflects differences in chemical composition. Air may darken the color. Nondiagnostic color may result from bacteria or fungi. Pertains to Heartwood (older, usually darker, central region of stem). Reflects differences in chemical composition. Air may darken the color. Nondiagnostic color may result from bacteria or fungi. Best assessed by odor of freshly exposed heartwood. Distinct odors are due to volatile extraneous substances in the wood. Odors fade upon exposure to air. Since the human tongue's sensory organs are spatially segregated, taste wood by pressing a piece large enough to cover all sensory areas. Avoid splinters. Includes P. strobus, P. monticola. Pinus lambertiana Includes P. palustris, P. echinata, P. taeda, P. elliottii, P. rigida. Pinus contorta Pinus banksiana Pinus resinosa Includes P. abies, P. jezoensis, P. obovata, P. glauca, P. rubra, P. mariana, P. engelmannii, P. sitchensis. Includes A. alba, A. balsamea, A. fraseri, A. amabilis, A. concolor, A. grandis, A. lasiocarpa, A. magnifica, A. procera, A. nobilis, A. pindrow. Includes T. canadensis, T. heterophylla, T. mertensiana. Sequoia sempervirens Calocedrus decurrens Thuja plicata Chamaecyparis nootkatensis Chamaecyparis lawsoniana Thuja occidentalis Chamaecyparis thyoides Juniperus virginiana Taxodium distichum Includes L. laricina, L. occidentalis, L. sibirica, L. kaempferi. Pseudotsuga menziesii Pinus ponderosa