#7 Hardwood structure [相容模式]web.nchu.edu.tw/pweb/users/eric/lesson/2408.pdf · 2017. 2....

Hardwood StructureHardwood Structure

JyhJyh--Horng WuHorng Wu

Softwood (Summary)Softwood (Summary)( )( )


Softwood (Summary)Softwood (Summary)( )( )


Softwood vs. Hardwood StructureSoftwood vs. Hardwood Structure

SOFTWOODSSOFTWOODS HARDWOODSHARDWOODSConductionConduction Longitudinal tracheid Vessel element

SupportSupport Longitudinal tracheid Fibers

StorageStorage Parenchyma (ray) Parenchyma

RaysRays Always narrow Rays short & narrow to wide & tall varies bywide & tall, varies by

species








Softwood versus HardwoodSoftwood versus Hardwood

Hardwood ray widths vary within and betweenHardwood ray widths vary within and between species.



Straight radial rows of cells characterize softwoods,Straight radial rows of cells characterize softwoods,but generally not hardwoods.



Softwood cells are aligned in straight radial rows in parallel form, with straight spoke-like rays,

h f ll i f d b i l f ifeach row of cells is formed by a single fusiform initial in the cambium.

H d d ld li d i t i htHardwood rays are seldom aligned in straight radial rows. Deviations occur in the vicinity of large vessel elements.g

After formation, vessel elements may expand 2 to 50 times their original diameter, pushing other g p gcells out of radial alignment.



Hardwood fibers areshorter than

ft d t h idsoftwood tracheids.

Softwood tracheids f d fare preferred for

paper, since longer fiber length isgimportant for paperstrength. The softwood tracheids

average 3-4 mm in length; hardwood fibers, in contrast, have an average length of less than 1 mm.



Th t “h d d” d “ ft d” hThe terms “hardwood” and “softwood” have no relevance to the actual hardness of the wood produced.p

Many softwoods produce wood that is harderand denser than wood produced by somep yhardwood.


Longitudinal CellsLongitudinal Cellsgg

Although longitudinal cells of hardwoods vary considerably in size and general configuration allconsiderably in size and general configuration, all these different cell types can be produced by a single fusiform initial in the cambiumsingle fusiform initial in the cambium.

Newly produced cells appear quite similar.

The differences between types develop during the process of cell maturation.





Vessel elements (Pores)Vessel elements (Pores) Unique cells ofUnique cells ofVessel elements (Pores)Vessel elements (Pores)--Unique cells of Unique cells of hardwoodshardwoods

Vessel – articulated, tube-like structure of indeterminate length in porous woods; formed g pthrough the fusion of the cells in a longitudinal row and perforation of common walls in a number of ways.

Vessel Element – one of the cellular components of a vessel.


Longitudinal CellsLongitudinal CellsggVesselVessel

Function - transport of water and mineral saltsAlways present

3 25 % by weight– 3-25 % by weight– 5-60 % by volumeVessels - couple of mm in length to several esse s coup e o e g o se e ameters longVessel elements - short, thin cell wall & large diameter cells– 0.3-1.0 mm long

50 500 µm diameter– 50-500 µm diameterPerforation plates


Longitudinal CellsLongitudinal CellsggVesselVessel

Vessel elements link end to end along the grain to form vessels.

Vessels are not arranged in precise parallel and vertical alignment.

This arrangement ensures that each branch of the crown receives water from many different roots, providing a safety feature against crown damage f t dfrom root damage.



Pores (Vessel) DistributionPores (Vessel) DistributionPores (Vessel) DistributionPores (Vessel) DistributionRingRing--Porous Wood Porous Wood ((環孔材環孔材))

poro s ood in hich theporous wood in which the pores formed at the b i i f th ibeginning of the growing season (in the early wood)

h l th thare much larger than those farther out in the ring, if the t iti f t thtransition from one to the other type is abrupt.



DiffuseDiffuse Porous WoodPorous Wood ((散孔材散孔材))

Pores DistributionPores Distribution

DiffuseDiffuse--Porous Wood Porous Wood ((散孔材散孔材))

A hardwood in which thepores exhibit little or novariation in size within agrowth ring, as viewed in across section.

The majority of hardwoods are diffuse-porous.


Longitudinal CellsLongitudinal CellsggPores DistributionPores Distribution



SemiSemi RingRing Porous WoodPorous Wood

Pores DistributionPores Distribution

SemiSemi--RingRing--Porous Wood Porous Wood ((半散孔材半散孔材))

Wood intermediate between diffuse porousbetween diffuse-porous and ring porous wood.


Longitudinal CellsLongitudinal CellsggPores DistributionPores Distribution



Pore ArrangementPore ArrangementPore ArrangementPore ArrangementSolitary poreSolitary porea single pore that doesa single pore that does not touch any others.

Maple (Maple (AcerAcer spp.)spp.)



Pore MultiplePore Multiple

Pore ArrangementPore Arrangement

Pore MultiplePore Multipletwo or more porescome in contact with Cottonwood Cottonwood come in contact with one another, typically, in radial alignment

((PopulusPopulusdeltoidesdeltoides))

in radial alignment.

JelutongJelutong((DyeraDyeracostulatacostulata))costulatacostulata))



Pore ChainsPore Chains


Pore ChainsPore ChainsA distinct radial series oralignment of several toalignment of several tomany solitary pores orpore multiplespore multiples.

Holly (Holly (冬青冬青) () (Ilex Ilex sppspp..))



Nested Pores (clusters)Nested Pores (clusters)


Nested Pores (clusters)Nested Pores (clusters)Pore multiples where larger numbers of pores contactnumbers of pores contact one another both radially and tangentiallyand tangentially.

Kentucky Coffeetree Kentucky Coffeetree ((Gymnocladus dioicusGymnocladus dioicus))



Wavy Bands (ulmiform)Wavy Bands (ulmiform)


Wavy Bands (ulmiform)Wavy Bands (ulmiform)Pores arranged in undulating bands approximately parallel tobands approximately parallel to the growth rings, characteristic of elm and hackberryof elm and hackberry.

American Elm American Elm ((Ulmus alataUlmus alata))


(( ))

Longitudinal CellsLongitudinal CellsggPore ArrangementPore Arrangement



EndEnd toto End Vessel ConnectionsEnd Vessel ConnectionsEndEnd--toto--End Vessel ConnectionsEnd Vessel Connections

One of the primary functions of vessels are as avenues of conduction.

Common end walls of longitudinally linked vesselCommon end walls of longitudinally linked vessel elements are perforated by unrestricted holes.

These perforations form in the perforation plateThese perforations form in the perforation plate near the end of the cell maturation process, as certain enzymes dissolve portions of the perforationcertain enzymes dissolve portions of the perforation plate.



Th f ti i

EndEnd--toto--End Vessel ConnectionsEnd Vessel Connections

These perforations vary in appearance:

SimpleSimple–– SimpleSimple

–– ScalariformScalariform

–– ForaminateForaminate


Longitudinal CellsLongitudinal CellsggEndEnd--toto--End Vessel ConnectionsEnd Vessel Connections

Si lSi l f tif ti

A i l d ll

SimpleSimple perforationperforation

A single and usually large and more or lessrounded opening inrounded opening in the perforation plate.

Best viewed inBest viewed in tangential section

American Basswood American Basswood ((Tilia americanaTilia americana))



ScalariformScalariform

A perforation plate with

ScalariformScalariformPerforation PlatePerforation Plate

A perforation plate with multiple elongated and parallel perforations, p p ,with bar-like remnantsof the plate between openings.

Best viewed in radial section

Red Alder (Red Alder (Alnus RubraAlnus Rubra))





Foraminate Foraminate (Reticulate)(Reticulate)PerforationPerforation PlatePlate

A multiple perforation plate, with netlike appearance.

Sparkleberry Sparkleberry ((VacciniumVaccinium arboreumarboreum))



Intervessel pittingIntervessel pittingIntervessel pittingIntervessel pitting

Pitting betweenadjacent vesselelements.

When vessels are in multiples, there will bepbordered pits along their common walls.



Intervessel Pitting ArrangementIntervessel Pitting ArrangementIntervessel Pitting ArrangementIntervessel Pitting Arrangement

(交互壁孔) (對列壁孔) (梯狀壁孔)


Longitudinal CellsLongitudinal CellsggIntervessel Pitting ArrangementIntervessel Pitting Arrangement

Alternate PittingAlternate Pitting – pits that are crowded together resulting in an irregular or diagonal arrangement.

AspenAspen YellowYellow--PoplarPoplar MagnoliaMagnolia


pp YellowYellow PoplarPoplar gg




Opposite PittingOpposite Pitting – short rectangular or slightly rounded pits in distinct horizontal arrangement.





Scalariform PittingScalariform Pitting – Elongated bar-like pits in parallel, ladder-like arrangement.






Longitudinal CellsLongitudinal CellsggTylosesTyloses

TylosesTyloses ((塡充物塡充物))TylosesTyloses ((塡充物塡充物))Saclike or cystlike structures that sometimes develop in a a so e es de e op avessel and rarely in a fiber through the proliferation of the protoplast of a parenchymaprotoplast of a parenchyma cell through a pit pair.



TylosesTyloses ((塡充物塡充物))

TylosesTyloses

TylosesTyloses ((塡充物塡充物))

Tyloses are usually formed in the inner sapwood, just prior to its transformation into heartwood. This is a normal physiological process that occurs in many species of hardwoods.occurs in many species of hardwoods.

They commonly form in hardwoods as a result of wounding and effectively act to prevent waterprevent waterwounding and effectively act to prevent water prevent water lossloss from the area around damaged tissues.

They may also develop as a result of infection y y pfrom fungi or bacteria, again to prevent water loss.



B bbl lik

TylosesTyloses

Bubble-like structures that form in the vesselform in the vessel elements of certain hardwood species, usually i j tiin conjunction with heartwood formationformation.

Black locustBlack locust



Tyloses partially or

TylosesTyloses

Tyloses partially orcompletely block the vessels in which they occur.

– This makes species likeThis makes species like white oak preferred in the manufacture of barrels, casks and tankscasks, and tanks.

– This makes white oak difficult to dry or impregnate with decayimpregnate with decay preventive or stabilizing chemical. White OakWhite Oak


White OakWhite Oak


Which one is White Oak?

TylosesTyloses


A B


B



TylosesTyloses


A BB



Two distinct types of hardwood tracheids are recognized;Two distinct types of hardwood tracheids are recognized; these are vascular vascular tracheidstracheids and vasicentricvasicentric tracheidstracheids

Vascular Vascular tracheidstracheids ((導管狀管胞導管狀管胞) ) This cell has a shape like a vessel element but lacks lacks perforationsperforations in the end walls, having instead bordered bordered pitspits in this location similar to those found in fibers. Vascular tracheids with spiralsspirals are found in UlmusUlmus (榆屬)Vascular tracheids with spiralsspirals are found in UlmusUlmus (榆屬) and CeltisCeltis (朴樹屬). Since vascular tracheids when cut transversely haveSince vascular tracheids, when cut transversely, have the same appearance as pores, they cannot be distin-guished from true pores in the cross section of wood.


g p


VasicentricVasicentric TracheidsTracheids ((周圍狀管胞周圍狀管胞))

Short irregularly shaped fibrous cells withShort, irregularly shaped fibrous cells with conspicuous bordered pits; vasicentricvasicentric tracheidstracheidsabound in the proximity of the large early-woodabound in the proximity of the large early-wood vessels of certain ring-porous hardwoods (e.g., oaks and chestnuts); they differ from vascularvascularoaks and chestnuts); they differ from vascular vascular tracheidstracheids (導管狀管胞導管狀管胞) not only in shape (tapering or rounded ends) but in arrangement (they are ) g ( ynot arranged in definite longitudinal rows like vascular tracheids).



Forms a light colored tissue seen with hand lens

VasicentricVasicentric TracheidsTracheids

Forms a light colored tissue seen with hand lens.


Longitudinal CellsLongitudinal CellsggHardwood Hardwood tracheidstracheids


Longitudinal CellsLongitudinal CellsggFibersFibers

FibersFibersFibersFibersThe term fiberfiber is often used in a general way to refer to all wood cells isolated in pulpingto refer to all wood cells isolated in pulping processes.

However in the context of woodHowever, in the context of wood morphology, the term fiberfiber refers to a specific cell type. p yp

Thus fibers, or fiber fiber tracheidstracheids as they are more properly called, are long, tapered. p p y g pand usually thick-walled cells of hardwood xylem.



FibersFibers

Function - mechanical support

FibersFibers

Always presentAbundant40 90 % b i ht40-90 % by weight– 20-75% by volumeLong needle like cellsLong, needle-like cellsThickened walls, heavily lignified– 0 5-1 5 mm long– 0.5-1.5 mm long– 20-30 µm diameter



Two types of fibers are

FibersFibers

Two types of fibers are recognized,

fiberfiber tracheidstracheids andfiber fiber tracheidstracheids and libriformlibriform fibersfibers.

– Fiber tracheids with bordered pits.

– Libriform fibers (a variation of the fiber) with simple pitswith simple pits.

(Libriform fibers occur in considerable numbers in some species )


species.)


Fiber Fiber tracheidstracheids細胞較短，細胞腔大，細胞壁較薄，具重緣壁孔重緣壁孔

(其重緣壁孔具有凸鏡狀或線狀之孔口) 輸導性能(其重緣壁孔具有凸鏡狀或線狀之孔口)。輸導性能

大於機械性能。

LibriformLibriform fibersfibers細胞長度長，細胞腔小，細胞壁厚，具有小型單壁單壁

孔孔，且其數量亦少。機械性能大於輸導性能。

許多樹種其纖維狀管胞與真木纖維間可看到有階段狀中間許多樹種，其纖維狀管胞與真木纖維間可看到有階段狀中間型的存在，兩者間難於有明顯的區別。



SEM i h f A h h iSEM micrograph of Acer saccharum showinglibriformlibriform fibersfibers with simple pitssimple pits which are more common on the radial walls (arrow).



f fi i i f ifi if ifi iBoth types of fibers exhibit a number of modificationsa number of modifications, some of which are of diagnostic value.

For instance, Califonia-laurel [Umbellulariacalifornica (Hook. & Arn.) Nutt.], thin transverse walls (septa) form in fibers, resulting in septateseptatelibriformlibriform fibersfibers or or fiber fiber tracheidstracheids. .

Such transverse walls extend only to the inner surface of the lateral secondary walls of the fiber, di idi th fib i t tdividing the fiber into two or more compartments



Aucoumea klaineana(Burseraceae) P.E. Gasson

Aucoumea klaineana(Burseraceae) K. Ogata

Aucoumea klaineana(Burseraceae) K. Ogata



th difi ti fAnother modification of fibers consists of the gelatinous fibersgelatinous fibers((膠質纖維膠質纖維))gelatinous fibersgelatinous fibers((膠質纖維膠質纖維), ), encountered mostly in encountered mostly in tension wood of hardwood,tension wood of hardwood,

(These fibers differ from the normal kind in possessing an innermost cell wall layer which differs in physical and chemical properties from thechemical properties from the usual secondary cell wall layer.)



Hardwood fibers are similar to softwood tracheids with these differences:with these differences:

– Hardwood fibers are rounded in cross section compared to the nearly rectangular shape of softwood tracheids.

– Fibers are typically thick walled and have bordered pits with less-developed borders than softwood tracheids.





Fibers appear as dark masses whendark masses when viewed with a handlens



Fiber Functions

FibersFibers

Fiber Functions

Softwood tracheids are responsible for d ti d d t thconduction and wood strength.

In hardwoods vessel elements are responsible for conduction, while the thick-walled fibers are responsible for mechanical support.

Density and strength of hardwoods is generally related to the portion of wood volume occupied by fibers relative to that accounted for by vessels.



ParenchymaParenchymaParenchymaParenchymaParenchyma cells

thi ll dare thin-walled storage units.

In hardwoods, parenchyma is long, tapered longitudinaltapered longitudinal cells, brick shaped epithelium around pgum canals, and ray cells.


Longitudinal CellsLongitudinal CellsggParenchymaParenchyma

Function - storageAlways presentAlways presentSmall & thin walled cells

50 150 m long– 50-150 µm long– 20-30 µm diameterRemain alive in sapwood (when functioning)Simple pits



Apotracheal ParenchymaApotracheal Parenchyma (獨立薄壁組織) –axial parenchyma cells which are separated from the pores by rays or fibers.

Paratracheal ParenchymaParatracheal Parenchyma (隨伴型薄壁組織) –axial parenchyma the cells of which are obviously associated with the vessels (pores in cross section).



Apotracheal ParenchymaApotracheal Parenchyma ArrangementArrangementApotracheal ParenchymaApotracheal Parenchyma ArrangementArrangement



Apotracheal ParenchymaApotracheal Parenchyma ArrangementArrangement

ParenchymaParenchyma


Diffuse ParenchymaDiffuse ParenchymaDiffuse ParenchymaDiffuse Parenchyma(分散狀薄壁組織)–single isolatedsingle, isolated apotracheal parenchymaparenchyma. Typically cannot be seen without aseen without a microscope.






DiffuseDiffuse--inin--Aggregates Aggregates ParenchymaParenchyma (短切線狀薄壁組織) –apotracheal parenchyma p p yoccurring in short tangential lines. Seen with a microscope in pbasswood and birch, visible with hand lens in black walnut and butternut.






Banded Banded ParenchymaParenchyma (帶狀薄壁組

織) – forming concentric lines or bands. It could be further differentiated into apotracheal apotracheal bandedbanded, if mainly independent y pof the pores; paratracheal paratracheal bandedbanded, if definitely associated , ywith the pores.



ParatrachealParatracheal Parenchyma ArrangementParenchyma ArrangementParatracheal Paratracheal Parenchyma ArrangementParenchyma Arrangement



ParatrachealParatracheal Parenchyma ArrangementParenchyma ArrangementParatrachealParatracheal Parenchyma ArrangementParenchyma Arrangement

Scanty ParatrachealScanty Paratracheal (隨伴Scanty ParatrachealScanty Paratracheal (隨伴

分散型) – Paratracheal parenchyma confined toparenchyma confined to a few cells around the vessels (ex , birch, maple)vessels (ex., birch, maple). Cannot be seen with hand lens magnificationhand lens magnification.



ParatrachealParatracheal Parenchyma ArrangementParenchyma Arrangement

Paratrachael Paratrachael


VasicentricVasicentric(周圍狀型) –parenchyma cells numerous enough to form a complete or partially complete sheath around a pore.

White AshWhite Ash




Aliform ParenchymaAliform Parenchyma


(翼狀型) – Vascentric Vascentric parenchymaparenchymathat occurs in a well that occurs in a well developed layer withdeveloped layer with

RaminRamin

additional cells additional cells forming tangential forming tangential wingwing--like extensions like extensions on either side.on either side.




Paratracheal ConfluentParatracheal Confluent ((連合翼連合翼


狀型狀型) ) –– Parenchyma that forms Parenchyma that forms a continuous tangential or a continuous tangential or diagonal zone connecting two diagonal zone connecting two or more pores.or more pores.

HoneylocustHoneylocust


yy



Banded Banded PParenchymaarenchyma ––


distinctdistinct tangential lines of tangential lines of cells, usuallycells, usually occurring occurring with fairly regularwith fairly regular spacing.spacing.

HickoryHickory


HickoryHickory



Unilaterally ParatrachealUnilaterally Paratracheal Aliform ConfluentAliform Confluent


((帽狀型帽狀型)) ((翼狀-連合翼狀型連合翼狀型))




Marginal ParenchymaMarginal Parenchyma ––


parenchyma occurringparenchyma occurring at at the growththe growth--ringring boundary,boundary,sometimessometimes called initial or called initial or terminalterminal parenchyma.parenchyma.Conspicuous in yellowConspicuous in yellowpoplarpoplar and Americanand Americanmahogany.mahogany.

Eastern cottonwoodEastern cottonwood




Marginal ParenchymaMarginal Parenchyma ––


Eastern cottonwoodEastern cottonwood





Inclusions in Parenchyma CellsInclusions in Parenchyma CellsInclusions in Parenchyma CellsInclusions in Parenchyma Cells

The cells of parenchyma frequently contain inclusions; these materials may be crystals, silicacrystals, silica, and numerous amorphous materialsamorphous materials of complex chemical nature, pp pincluding gums, resins, tannins, oils, latex, coloring matter, and nitrogenous materials, such as alkaloids.g

CarbohydratesCarbohydrates, usually in the form of starch grains, are also common, particularly in the sapwood portion of the stem.



Inclusions in Parenchyma CellsInclusions in Parenchyma CellsInclusions in Parenchyma CellsInclusions in Parenchyma Cells

Frequently the color, odor, and taste of wood are traceable to these products.

C t lC t l tl f l i l tl i l t itCrystalsCrystals, mostly of calcium oxalatecalcium oxalate, are quite common, both in the longitudinal parenchyma and i th llin the ray cells.

The most common shape of such crystals isThe most common shape of such crystals is rhomboidal (長斜方形).




Longitudinal CellsLongitudinal CellsggGum CanalsGum Canals

Gum CanalsGum CanalsGum canalsGum canals in porous woods, when present, may be in porous woods, when present, may be normalnormal or ofor of traumatictraumatic (wound) origin(wound) origin

Normal gum canalsNormal gum canalsnormalnormal or of or of traumatictraumatic (wound) origin.(wound) origin.

N l l th iti iN l l th iti iNormal gum canals occupy the same position in porous Normal gum canals occupy the same position in porous woods as the resin canals of conifers; woods as the resin canals of conifers; ii..ee., they extend ., they extend with the grain embedded in longitudinal elements orwith the grain embedded in longitudinal elements orwith the grain, embedded in longitudinal elements, or with the grain, embedded in longitudinal elements, or across the grain, included in the wood rays.across the grain, included in the wood rays.

The two types however areThe two types however are seldom present in theseldom present in theThe two types, however, are The two types, however, are seldom present in the seldom present in the same woodsame wood; i; i..ee., the canals in a given hardwood are ., the canals in a given hardwood are usually usually either either longitudinallongitudinal or or transversetransverse..


yy gg


Normal longitudinal canals for instance featureNormal longitudinal canals for instance feature thetheNormal longitudinal canals, for instance, featureNormal longitudinal canals, for instance, feature the the dipterocarpdipterocarp woods of the Indowoods of the Indo--Malayan region. Malayan region.

Traumatic gum canalsTraumatic gum canalsTraumatic canals in hardwoods Traumatic canals in hardwoods may form in may form in one of two one of two waysways, , or by a combination or by a combination of theseof these, and they are , and they are restricted to the longitudinal kind only. restricted to the longitudinal kind only.

One kind of traumatic canals in hardwoods is of a One kind of traumatic canals in hardwoods is of a schizogenousschizogenous nature, of the same kind as in conifers; nature, of the same kind as in conifers; th lt f th ti f ll t th iddlth lt f th ti f ll t th iddlthey result from the separation of cells at the middle they result from the separation of cells at the middle lamellalamella. (Usually they are . (Usually they are arranged in tangential rowsarranged in tangential rows, , as viewed in cross section )as viewed in cross section )


as viewed in cross section.)as viewed in cross section.)


Traumatic gum canalsTraumatic gum canalsTraumatic gum canalsTraumatic gum canalsOthers are formed through the actual disintegration Others are formed through the actual disintegration (gummosis) of cell walls, in which case they are called(gummosis) of cell walls, in which case they are called(gummosis) of cell walls, in which case they are called (gummosis) of cell walls, in which case they are called lysigenouslysigenous canals.canals.

In some cases traumatic canals are formedIn some cases traumatic canals are formed as a resultas a resultIn some cases traumatic canals are formedIn some cases traumatic canals are formedas a result as a result of both these processes; i.e., the cavity first forms of both these processes; i.e., the cavity first forms through cell fusion andthrough cell fusion andseparation of cells at the middle separation of cells at the middle lamella, followed by the enlargement of the cavity lamella, followed by the enlargement of the cavity through gummosis of the cells immediately surrounding through gummosis of the cells immediately surrounding it Thi ki d f l f ti i d ib dit Thi ki d f l f ti i d ib dit. This kind of canal formation is described as it. This kind of canal formation is described as schizolysigenousschizolysigenous. .





Traumatic gum canalsTraumatic gum canalsTraumatic gum canalsTraumatic gum canals

The traumatic The traumatic schizogenousschizogenous canals canals of hardwoods are of hardwoods are provided with provided with epitheliumepithelium,,the same as the normal the same as the normal canalscanals; those of ; those of lysigenouslysigenous origin are devoid of itorigin are devoid of it. .

Since the Since the lysigenouslysigenous and and schizolysigenousschizolysigenous canals result canals result from cell disintegration, they arefrom cell disintegration, they aregenerally much larger generally much larger (often 1/8 inch or more in diameter) than the(often 1/8 inch or more in diameter) than the(often 1/8 inch or more in diameter) than the (often 1/8 inch or more in diameter) than the schizogenousschizogenous canals, and are often conspicuous to the canals, and are often conspicuous to the naked eye. naked eye. yy





Relative hardwood cell diameter and wall thickness


RaysRays


RaysRays


RaysRays


RaysRays

Ray WidthRay WidthRay WidthRay Width

In Hardwoods, Rays may be:

– UniserateUniserate – one cell wideBiserateBiserate two cells wide

In Hardwoods, Rays may be:

– BiserateBiserate – two cells wide– MultiserateMultiserate – many cells

widewide.

Ray width varies between yand within species.

Sugar MapleSugar Maple


RaysRays

On a tangential surface a ray thatOn a tangential surface, a ray that consists of a single vertical series of cells – one cell wide ray – is a uniseriateuniseriate ray. yIf is two cells wide, it is a biseriate ray, and if it is three or more cells wide it is multiseriate.


RaysRays

Hardwood Ray Parenchyma CellsHardwood Ray Parenchyma CellsHardwood Ray Parenchyma CellsHardwood Ray Parenchyma Cells

Function - transport and storageFunction transport and storageAlways presentHeight - few to many cells highe g e o a y ce s g– 50 μm to several cmSimple pitsp p


RaysRays

Hardwood Ray Parenchyma CellsHardwood Ray Parenchyma CellsHardwood Ray Parenchyma CellsHardwood Ray Parenchyma Cells

Soft oods ra sSoft oods ra s ma contain ra tracheidsra tracheids as ellSoftwoods raysSoftwoods rays may contain ray tracheidsray tracheids as well as ray parenchymaray parenchyma, where hardwood rays consist hardwood rays consist

ti l f h llti l f h llentirely of ray parenchyma cellsentirely of ray parenchyma cells.

There are two types of ray parenchyma cellstwo types of ray parenchyma cells in yp y p yyp y p yhardwoods.


RaysRays

Ray cellsRay cellsRay cellsRay cells

In radial view, procumbent ray cellsprocumbent ray cells(橫臥木質線細胞) are elongated horizontally.

Upright ray cellsUpright ray cells (直立Upright ray cellsUpright ray cells (直立

木質線細胞) are either squarish or verticallysquarish or vertically oriented.

YellowYellow--poplarpoplar


YellowYellow poplarpoplar

RaysRays

HeterocellularHeterocellularHeterocellularHeterocellularHardwood rays that contain both upright and contain both upright and procumbent ray cellsprocumbent ray cells are called heterocellularheterocellular or heterogenousheterogenous, where the upright cells are usually located in one or more rows along the margins of the rays. YellowYellow--poplarpoplar


YellowYellow poplarpoplar

RaysRays

HomocellularHomocellularHomocellularHomocellular

Homocellular or homogenous rays are composed of only one type of cells, typically only procumbent cells.

SycamoreSycamore


RaysRays


RaysRays

Node RaysNode RaysNode RaysNode RaysRays that swell at the growth-ring boundary.

BeechBeech


RaysRays

Node RaysNode RaysNode RaysNode Rays


RaysRays

Ray Width ComparisonsRay Width ComparisonsRay Width ComparisonsRay Width Comparisons

Comparing ray with to pore diameter quickly distinguishes species, like maple (the largest rays are about the same

iwidth as the largest pores) and birch (the l tlargest rays are narrower than the largest pores).

BirchBirch MapleMaple


RaysRays

(金鶯隊Mark Trumbo) (光芒隊 Evan Longoria) (美聯 MVP Mike Trout)


RaysRays

Widest ray is narrower than largest poreWidest ray is narrower than largest poreWidest ray is narrower than largest poreWidest ray is narrower than largest pore

BirchBirch


RaysRays

Widest rays are about the same as the largestWidest rays are about the same as the largestWidest rays are about the same as the largest Widest rays are about the same as the largest porespores

MapleMaple


RaysRays

Tangential and di l fradial surfaces

expose rays inmany species to the naked eye.

They give wood y ga certainaesthetic appeal.


RaysRays


RaysRays

PHILIPS CAPELLA TONMEISTER 785PHILIPS CAPELLA TONMEISTER 785(Tube radio)


Hardwood (Summary)Hardwood (Summary)( )( )


Hardwood (Summary)Hardwood (Summary)( )( )


Date post:	21-Feb-2021
Category:	Documents
Upload:	others
View:	3 times
Download:	0 times

#7 Hardwood structure [相容模式]web.nchu.edu.tw/pweb/users/eric/lesson/2408.pdf · 2017. 2....

Documents