Wood Anatomy Exam 2

main features used in softwood ID

resin canals, EW/LW transition, crossfield pitting type, ray tracheids, spiral thickenings, longitudinal trachied pittings, odor

Pinaceae

resinous and nonresinous

resinous pinaceae

soft pines (eastern white and sugar pine); hard pines (southern yellow pine, western yellow pines -- ponderosa, lodgepole--, red pine)

Pinus Strobus

heartwood: cream colored to light or dark reddish brown; darkens with age

grain: fairly even

odor: piney

resin canals: large, numerous

EW/LW transition: gradual

ray tracheids: smooth

crossfield pitting: fenestriform

- resin streaks sometimes present

Pinus lambertiana

heartwood: light to pale reddish brown, never dark reddish brown; does not darken with age

grain: fairly even

odor: resinous

resin canals: large, numerous

EW/LW transition: gradual

ray tracheids: smooth

crossfield pitting: fenestriform

- resin streaks typically present and prominent

Pinus spp.

heartwood: yellowish, orangish, or light brown

grain: uneven grain

odor: sharp 'pitchy' pine odor

resin canals: large, numerous

EW/LW transition: abrupt

ray tracheids: dentate

crossfield pitting: pinoid

- growth rings tend to be fairly wide

Pinus ponderosa

heartwood: yellowish to light reddish to orangish brown

grain: fairly uneven

odor: mild piney odor

resin canals: large, numerous

EW/LW transition: fairly abrupt

ray tracheids: dentate

crossfield pitting: pinoid

- narrower growth rings than SYP

- dimples can occur

Pinus resinosa

combination of dentate ray tracheids and fenestriform pits

Pinus contorta

smaller diameter logs than Pinus ponderosa

large resinous pinaceae

hard pines and soft pines

small resinous pinaceae

douglas-fir, larch, spruce

non resinous pinaceae

eastern hemlock, true-firs

cupressaceae

baldcypress, redwood, cedars

Pseudotsuga menziesii

heartwood: reddish brown

grain: uneven

odor: like plywood

resin canals: small, sparse

EW/LW transition: abrupt

ray tracheids: smooth

crossfield pitting: piceoid

- wavy growth rings sometimes occur

- spiral thickenings

Larix occidentalis

heartwood: russet to reddish brown

grain: uneven

resin canals: small, sparse

EW/LW transition: abrupt

ray tracheids: smooth

crossfield pitting: piceoid

- can be waxy or greasy

- paired pits

Picea spp.

heartwood: light colored (not distinct from sapwood)

grain: moderately even to uneven

resin canals: small, sparse

EW/LW transition: gradual

ray tracheids: smooth

crossfield pitting: piceoid

- can be lustrous

Tsuga canadensis

heartwood: light colored (not distinct from sapwood)

grain: uneven

resin canals: absent

EW/LW transition: abrupt-to-gradual

ray tracheids: smooth

crossfield pitting: piceoid/cupressoid

- will crumble when cut on transverse

Abies spp.

heartwood: light colored (not distinct from sapwood)

grain: moderatley even to uneven

resin canals: absent

EW/LW transition: gradual

crossfield pitting: taxodioid

- no ray tracheids

Sequoia sempervirens

heartwood: medium to deep reddish brown

grain: fairly uneven

resin canals: absent

EW/LW transition: abrupt

crossfield pitting: taxodioid

- coarse texture

- occasionally 3+ pits on longitudinal tracheids

Taxodium distichum

heartwood: from yellowish to light, reddish or dark brown

grain: uneven

odor: rancid

resin canals: absent

EW/LW transition: abrupt

crossfield pitting: taxodioid and cupressoid

- greasy feel

- coarse texture

- false rings common

- occasionally 3+ pits on longitudinal tracheids

Callitropsis nootkatensis

heartwood: yellow

grain: even

odor: raw potatoes

EW/LW transition: gradual

crossfield pitting: cupressoid

- fine texture

- exhibit entirely ray parenchyma and entirely ray tracheid homocellular rays

Calocedrus decurrens

heartwood: medium reddish to purplish brown

grain: moderately even

odor: pencil-like

EW/LW transition: gradual

crossfield pitting: cupressoid

- medium texture

Chamaecyparis lawsonia

heartwood: yellowish to pinkish brown

grain: fairly uneven

odor: ginger-like (vicks vaporub)

EW/LW transition: gradual

crossfield pitting: cupressoid

- medium texture

Chamaecyparis thyoides

heartwood: light brown with pinkish tone

grain: moderately even

odor: sweet and pleasant

EW/LW transition: gradual

crossfield pitting: cupressoid

- fine texture

- abundant zoneate parenchyma resembling false rings

Juniperus virginiana

heartwood: purplish red to reddish brown

grain: moderately uneven to fairly even

odor: cedar chest

EW/LW transition: gradual

crossfield pitting: cupressoid

- fine texture

- longitudinal parenchyma abundant and zoneate

Thuja plicata

heartwood: medium to dark brown or reddish brown

grain: moderately uneven

odor: sharp and sweet (chocolate-like?)

EW/LW transition: abrupt

crossfield pitting: taxodioid

- medium texture

Thuja occidentalis

heartwood: light to medium straw brown

grain: fairly even

odor: sharp but mild (balloon-like?)

EW/LW transition: gradual

crossfield pitting: taxodiod

- fine texture

taxodioid crossfield pitting

western redcedar and northern white-cedar; true firs

cupressoid crossfield pitting

eastern redcedar, alaska-cedar, port-orford-cedar, incense-cedar, and atlantic white-cedar; eastern hemlock

piceoid crossfield pitting

douglas-fir, western larch, eastern spruce, eastern hemlock

pinoid crossfield pitting

southern yellow pines, ponderosa pine, lodgepole pine

fenestriform crossfield pitting

red pine, sugar pine, eastern white pine

wood is hygroscopic

intakes any water in its surroundings

moisture content (MC)

the ratio of the weight of water in the wood to its oven-dry weight, expressed as a percentage

MC equation

(W1 - W0 / W0) x 100

W0 = oven-dry wight

W1 = starting weight

free water

liquid water in the cell of the lumen; easy to remove, won't return unless exposed to liquid water

bound water

water molecules bound in the cell wall through hydrogen bonds; most difficult to remove

after free water is gone

there will still be water vapor in lumen

saturated

as long as there is free water in the lumen, the cell wall will still be

relative humidity (RH)

the ratio of the moisture content of the air to the maximum possible moisture content at the same temperature

lose some of its bound water and eventually achieve EMC

if the relative humidity (RH) is less than 100%, the cell wall will

equilibrium moisture content (EMC)

no not loss or gain of moisture

fiber saturation point (FSP)

when the lumen contains no free water, but the cell walls are still fully saturated (only bound water)

capillary action

tendency of water to rise in a narrow space due to cohesion, adhesion, and surface tension; the smaller diameter of the capillary, the higher the water rises

water potential gradient

water moves from a locus of higher water potential to one of lower water potential

absorption

the process by which water is taken up into the physical structure of the tree

pits and perforation plates

how water moves from cell to cell up the tree

permeability

the rate of flow of liquids and gasses through xylem; heaviliy dependent on size of openings between cells (size of margo), much greater in longitudinal direction

reduced permeability

extractives, occlusions (tyloses), aspirated pits

adsorption

the process of binding or sticking to a surface; the amount of accessible OH groups for water molecules to create hydrogen bonds

amporphous regions

areas where most hydrogen bonding occurs; where water 'looks' for to attach to open OH/hydroxyl groups

diffusion

movement of molecules from an area of higher concentration to an area of lower concentration; driven by a moisture gradient in the wood -- moving water from the wetter center to the dryer surface wood

hysteresis

the lag between EMC and desorption and adsorption; the period between when hydrogen bonds occur -- when water molecules are finding OH groups to bind to

no impact on volume

addition or loss of free water has

shrinkage

loss of bound water

swelling

addition of bound water

swelling and shrinking

occurs mostly in tangential and radial directions

cause of shrinking and swelling

water molecules absorb to cellulose or hemicellulose molecules in the cell wall, pushing them apart in the process, increasing distance and causing dimensional change (vice versa for shrinkage)

S2

contributes most to shrinking and swelling due to its thickness; it's microfibril angle is almost completely vertical, so when cellulose molecules are pushed apart, swelling is in a lateral direction

lumen size in shrinking and swelling

stays constant; volumetric change is in the cell wall only

proportional to the amount of water los tor gained

the amount of shrinking or swelling done is

denser species

shrink and swell more, as they contain more wood (more cellulose, more molecules to push apart, etc)

double in the tangential direction

shrinkage is about

latewood

swells and shrinks more because it contains more cellulose; it dominates the tangential direction

irregular wood

reaction wood (compression and tension), juvenile wood, special figure, monocot

reaction wood

develops in leaning trees and most branches; a tree's physiological mechanism for redirecting growth to vertical -- compression wood and tension wood

compression wood

softwoods, on the lower side of a leaning stem; wide growth rings, thicker latewood, irregularly shaped stem with off-center pith common

compression wood microscopically

round tracheids, intercellular spaces, thicker and denser cell walls that have a greater proportion of lignin, spiral cavities, large microfibril angle (less vertical)

compression wood properties

denser, more brittle, more longitudinal shrinkage and swelling, can cause warp and twist

tension wood

hardwoods, upper side of a leaning stem or branch

tension wood microscopically

gelatinous fibers (usually in earlywood), greater proportion of cellulose than normal wood

tension wood properties

denser, strength problems, fuzzy grain, often 'silvery' appearance, greater longitudinal shrinkage and swelling, can cause warp and twist

juvenile wood

occurs in the first few growth rings surrounding the pith, develops within the first 1-15 years

juvenile wood macroscopically

often wide growth rings near pith, needle traces common

juvenile wood microscopically

shorter wood cells than mature wood, fewer latewood cells, microfibril angle of secondary wall is greater (less vertical)

juvenile wood properties

less dense, greater longitudinal shrinkage and swelling, warp and twist common, low strength, unpredictable

special figure

uncommon patterns or markings on longitudinal surfaces, often considered beautiful and/or valuable, used for decorative purposes; pigment figure, figure caused by irregular growth rings, figure caused by deviation in cell or grain direction

pigment figure

pigmented areas of the heartwood might not concentric with the growth rings

figure from irregular growth rings

caused by fluted, indented, furrowed rings, etc; can cause bear scratches, dimples, birds eye figure, blister figure

figure from deviation in grain or cell orientation

interlocked grain (striped figure), wavy grain (curly figure), bud formations (burls)

monocots

non-dicot angiosperms; bamboos, palm trees, rattan, yucca, etc

monocot properties

vascular cells arranged in bundles (instead of ring arrangements) and are surrounded by ground tissue (parenchyma cells); fibrovascular bundles contain vessels, fibers, phloem cells

medium to low

soft pine density

gradual EW/LW transition

soft pines have

exhibit dimples

lodgepole pine and ponderosa pine

exhibit conspicuous resin canals on longitudinal surfaces

sugar pine and eastern white pine

earlywood to latewood transition

you can differentiate hard pines from soft pines by their

dentate ray tracheids

hard pines always exhibit

fenestriform pitting

soft pines always have

occasionally has 3+ bordered pits

baldcypress and redwood

has abrupt transition from EW to LW

douglas-fir, redwood, western larch, baldcypress

distinct color difference between sapwood and heartwood

redwood, douglas-fir, larch

higher density, more purplish-brown color, finer texture

eastern redcedar has a

abrupt transition to EW/LW

western redcedar