• Porosity

• Pore Groupings

• Pore Arrangement

PORE = VESSEL IN CROSS SECTION

POROSITY

• RING POROUS

• DIFFUSE POROUS

• SEMI- RING POROUS(Semi-Diffuse Porous used in ID Book)

DEFINED BY SIZE DISTRIBUTION OF VESSELSWITHIN ONE GROWTH RING

(about same size throughout or larger in earlywood)and the

TRANSITION FROM EARLYWOOD TO LATEWOOD (gradual or abrupt).

RING POROUS

• Earlywood zone with widevessels (pores)

• Earlywood zone about samesize each year.

• Abrupt transition to latewoodzone with narrow vessels(pores), latewood zone variablewidth

• Common in temperate USwoods, rare in tropical trees.

Ash, Fraxinus

Red Elm, Ulmus rubra

DIFFUSE POROUS• Vessel diameter about the same in earlywood and

latewood

• Vessels throughout growth ring.

• Growth rings less obvious than in ring porouswoods

Yellow Poplar, Liriodendron tulipifera Birch, Betula sp.

DIFFUSE POROUSHOLLY, Ilex aquifolium BLACKGUM, Nyssa

Which one likely has the higher specific gravity?

Holly with less vessel volume

Persimmon Pecan

Diospyros virginiana Carya illinoisensis

SEMI-RING POROUSVessel diameter gradually decreases from earlywood to latewood

POREGROUPINGS

• SOLITARY

• RADIAL MULTIPLES

• CLUSTERS

VESSEL GROUPINGS: Solitary

Handlens View of Red OakAll vessels solitary

Microscope view (10x objective)Tropical Vine. All vessels solitary

VESSEL GROUPINGS:Solitary and in Radial Multiples

Handlens view of Birch.Vessels solitary and inshort radial multiples

Microscope view (4x objective)Mahogany. White ovals surround some

radial multiples of 2 and 3 vessels

MMOOSSTT

CCOOMMMMOONN

VESSEL GROUPINGS: CLUSTERS

Handlens View of Black LocustLatewood vessels in clustersClusters connected by axial parenchyma

Cluster = a group of vessels, someside by side tangentially as well asradially.

Vessel clusters occur in combinationwith solitary vessels and radialmultiples.

Not common.

In U.S. woods, see in latewood ofsome ring porous species.

PORE ARRANGEMENT

• RANDOM

• TANGENTIAL LY

• RADIALLY

• OBLIQUE / DIAGONAL

• DENDRITIC / FLAMELIKE

NOTE: THESE VESSEL ARRANGEMENT PATTERNS OFTENINTERGRADE, ESPECIALLY RADIAL AND OBLIQUE / DIAGONAL

VESSEL ARRANGEMENT: Random

Handlens view of Birch (Betula).Random arrangement of vessels(vessels are solitary and in short

radial multiples )

Microscope view (10x objective)Tupelo (Nyssa ). Random arrangement

of vessels (vessels solitary & in shortradial multiples)

TANGENTIAL ARRANGEMENT

Handlens view. Ulmus americanaLatewood in wavy tangential bands,

solitary row of earlywood vesselsWide growth rings.

Microscope view (4x objective)American Elm. Narrow growth rings,earlywood solitary row, latewood with

tangential bands of vessels.

RADIAL to DENDRITIC

Handlens view. White oak.Latewood with very small vessels in a

radial to dendritic arrangement

Handlens view. ChestnutLatewood with very small vessels in a

radial to oblique to dendriticarrangement

Arrangement of Vessels: RADIAL to DIAGONAL / OBLIQUE

Handlens view. Tropical HardwoodVessels in diagonal pattern

Handlens view. Red OakLatewood vessels in radial-diagonal pattern