Tree BiologyTree BiologyAndrew SaundersAndrew Saunders

Georgia Urban Forest CouncilGeorgia Urban Forest CouncilArborist Certification Study ClassArborist Certification Study Class

06/12/201306/12/2013

What is a Tree?What is a Tree?Woody plants that are large and have a single Woody plants that are large and have a single trunktrunk

Woody, single stemmed plants, growing at Woody, single stemmed plants, growing at least 10least 10’’ talltall

A plant with an elongated stems or trunk, A plant with an elongated stems or trunk, supporting leaves or branches. supporting leaves or branches.

Is a crapemyrtle a tree?

Two Types of TreesTwo Types of Trees

GymnospermsGymnosperms-- plants with seeds plants with seeds exposed i.e.: pine and spruceexposed i.e.: pine and spruce

AngiospermsAngiosperms-- plants with seeds plants with seeds borne in an ovary i.e.: hardwoodsborne in an ovary i.e.: hardwoods--oaks, persimmon, dogwood, etc. oaks, persimmon, dogwood, etc.

How do Trees Grow?How do Trees Grow?

MeristemsMeristems-- sites of rapid cell division in the sites of rapid cell division in the shoot tips, root tips and cambiumshoot tips, root tips and cambium

Primary (Apical) MeristemsPrimary (Apical) Meristems-- elongation of elongation of shoots and rootsshoots and roots

Located at the endsLocated at the ends-- in shoots inside in shoots inside Buds Buds and behind and behind the the root caproot cap

Secondary (Lateral) MeristemsSecondary (Lateral) Meristems-- increase increase diameter diameter

CambiumCambium-- vascular system vascular system --produces produces XylemXylem to the to the inside and inside and PhloemPhloem to the outsideto the outsideCork CambiumCork Cambium-- barkbark

Apical MeristemsApical MeristemsRoots Shoots

Vascular Cambium

Phloem

Cork Cambium

Cork

Bark

Sapwood

HeartwoodXylem

Lateral Lateral MeristemsMeristems

QuizQuiz

1. An ______________ ____________ is 1. An ______________ ____________ is protected by the root cap. protected by the root cap.

Apical Meristem

2. This type of tree protects its seed in a fleshy ovary. Angiosperm

3. The vascular cambium is creates the _________ and the __________. Xylem Phloem

Tree Vascular SystemsTree Vascular Systems

Xylem Xylem -- wood of treewood of tree-- conducts water and conducts water and dissolved minerals, supports, storage, defensedissolved minerals, supports, storage, defense

Phloem Phloem –– food supply line food supply line -- responsible for the responsible for the movement of sugars within the tree. movement of sugars within the tree.

Lenticels Lenticels –– small openings in bark which aid in small openings in bark which aid in gas exchange. gas exchange.

Supportive Components of XylemSupportive Components of Xylem

Fibers Fibers –– xylem cells used xylem cells used exclusively to provide exclusively to provide mechanical strengthmechanical strength

Parenchyma Cells Parenchyma Cells –– cells in cells in the outer xylem which aid in the outer xylem which aid in water conduction, store water conduction, store carbohydrates, and defend carbohydrates, and defend against decayagainst decay

Vascular Components of XylemVascular Components of Xylem

Tracheids Tracheids –– the elongated, the elongated, dead cells with pointy ends dead cells with pointy ends which aid water conduction which aid water conduction and mechanical supportand mechanical support

Vessels Vessels –– highly efficient highly efficient water conducting cellswater conducting cells found found exclusively in Angiosperms exclusively in Angiosperms

VesselsVesselsRingRing PorousPorous-- wide vessels early in the growing wide vessels early in the growing season and narrower later (ex: elms, oaks, ashes)season and narrower later (ex: elms, oaks, ashes)

DiffuseDiffuse PorousPorous-- vessels of uniform size (maples, vessels of uniform size (maples, planetrees, poplars)planetrees, poplars)

Sections of the XylemSections of the Xylem

SapwoodSapwood-- xylem that xylem that conducts water conducts water –– many many living parenchyma cells living parenchyma cells in the sapwoodin the sapwood

HeartwoodHeartwood-- further further inside the tree inside the tree -- nonnon--conducting tissue that is conducting tissue that is darker darker

Sapwood

Heartwood

Growth RingsGrowth Rings

Visible in the xylemVisible in the xylemRings are a result of seasonal production of xylem Rings are a result of seasonal production of xylem by the cambiumby the cambiumAppear as rings because the relative size and Appear as rings because the relative size and density of the vascular tissue changes throughout density of the vascular tissue changes throughout the growing seasonthe growing seasonCells produced early in the season (earlywood) vs Cells produced early in the season (earlywood) vs produced later (latewood) allows for diameter produced later (latewood) allows for diameter increase within an individual year to be seenincrease within an individual year to be seen

Early Wood

(Spring)

Late Wood

(Summer)

QuizQuiz

1. Name the four types of xylem cells? 1. Name the four types of xylem cells?

2. The _________ conducts carbohydrates.

3. A ___________ is a small opening in the stem to allow for gas exchange.

Tracheids, Fibers, Parenchyma Cells, Vessels

Phloem

Lenticel

RootsRoots4 functions: anchorage, storage, absorption, and 4 functions: anchorage, storage, absorption, and conductionconduction

Absorbing rootsAbsorbing roots-- small, fibrous, primary tissues that small, fibrous, primary tissues that grow at the ends of the main, woody roots. Root hairs grow at the ends of the main, woody roots. Root hairs aid in the uptake of wateraid in the uptake of water

Lateral rootsLateral roots-- horizontal roots, near soil surfacehorizontal roots, near soil surface

Sinker rootsSinker roots-- grow downward, providing anchorage grow downward, providing anchorage and increasing the soil used by the root systemand increasing the soil used by the root system

Tap rootTap root-- downward growing root on young treesdownward growing root on young trees

Root StructureRoot Structure

90% of roots are in the top 12” of soil

Improving Root EfficiencyImproving Root EfficiencyMycorrhizae Mycorrhizae –– (fungus (fungus roots) roots) -- fungi that fungi that improve root function. improve root function.

Symbiosis Symbiosis –– a relationship that benefits both participants.

Fungi derive Fungi derive nourishment from rootsnourishment from rootsFungi aid in water and Fungi aid in water and mineral absorptionmineral absorption

Absorbing Root FunctionAbsorbing Root Function

Absorbing roots are Absorbing roots are generated in generated in ““fansfans”” that that expand to exploit new expand to exploit new resourcesresourcesThese fans are active These fans are active even when the top of the even when the top of the tree is dormanttree is dormantTrees produce between Trees produce between 66--18 root fans annually 18 root fans annually depending on species depending on species and conditionsand conditions

QuizQuiz

1. 90% of roots are in the top ____ inches of soil. 1. 90% of roots are in the top ____ inches of soil.

2. ____________ is the symbiotic relationship between roots and fungi.

3. What are the four functions of roots?

12

Mycorrhizae

Anchorage, Storage, Conduction, Absorption

Types of BudsTypes of Buds

Terminal (apical) buds Terminal (apical) buds at the end of shootat the end of shootLateral (axillary) buds Lateral (axillary) buds occur along the stemoccur along the stem

Often Often dormantdormant. Pruning the terminal bud will . Pruning the terminal bud will often release the dormant axillary buds near the cutoften release the dormant axillary buds near the cut

Adventitious budsAdventitious buds-- produced along stems or produced along stems or roots where primary meristems not normally roots where primary meristems not normally found.found.

Epicormic ShootEpicormic Shoot-- when dormant buds elongate when dormant buds elongate and produce shootsand produce shoots

Terminal

Bud

Lateral

Bud

Epicormic Sprouts - off of adventitious buds

Stem MorphologyStem Morphology

NodeNode –– the enlarged portion of a stem where the enlarged portion of a stem where leaves and buds developleaves and buds developInternodeInternode –– the area between nodesthe area between nodesBundle ScarBundle Scar –– horizontal development along a horizontal development along a twig that indicate where the previous terminal twig that indicate where the previous terminal bud was located. Produced annuallybud was located. Produced annuallyLeaf ScarLeaf Scar –– the attachment point on a twig the attachment point on a twig where leaves were previously attachedwhere leaves were previously attached

Lateral

Bud

Terminal

Bud

Bundle Scar

Node

Internode

Current Year’s Growth

Leaf Scar

BranchesBranches

Branch collarBranch collar-- junction junction of the branch to the of the branch to the stemstem

In the crotch, branch In the crotch, branch and trunk expand and trunk expand against each other and against each other and bark is pushed up to bark is pushed up to form the form the Branch bark Branch bark ridgeridge

Included BarkIncluded Bark

If bark in the crotch is If bark in the crotch is surrounded by wood it surrounded by wood it is called is called included barkincluded bark

Weakens the crotch and Weakens the crotch and a normal brancha normal branch--toto--trunk trunk attachment is not formedattachment is not formedA high likelihood of A high likelihood of failures exists if the failures exists if the junction is not junction is not reinforced. reinforced.

Wound Effects and ResponseWound Effects and Response

CompartmentalizationCompartmentalization-- limit spread of limit spread of discoloration and decaydiscoloration and decayCODITCODIT-- Compartmentalization Of Decay In Compartmentalization Of Decay In TreesTrees

Forms 4 barrier Forms 4 barrier ““wallswalls””Wall 1 to Wall 3 = Wall 1 to Wall 3 = Reaction ZoneReaction ZoneWall 4 = Barrier Zone Wall 4 = Barrier Zone Wall 4 strongest and Wall 1 weakestWall 4 strongest and Wall 1 weakest

CODITCODIT-- 4 wall 4 wall responseresponse

QuizQuiz

1. An ____________ bud develops along stems 1. An ____________ bud develops along stems and roots where primary meristems are not and roots where primary meristems are not typically found. typically found.

2. This physiological feature is created where the tissues of a branch and stem come together.

3. What does CODIT stand for?

Adventitious

Branch Bark Ridge

Compartmentalization Of

Decay In Trees

LeavesLeaves

EvergreenEvergreen-- trees hold their leaves for more trees hold their leaves for more than one yearthan one yearDeciduousDeciduous-- trees that shed their leaves every trees that shed their leaves every yearyear

Usually in the fall as a result of cell changes and Usually in the fall as a result of cell changes and growth regulators that combine to form an growth regulators that combine to form an abscission zone abscission zone –– protects stem from desiccation protects stem from desiccation and pathogen entryand pathogen entry

LeavesLeaves

Food producers of the treeFood producers of the tree-- photosynthesisphotosynthesisChloroplastsChloroplasts are the leaf cells that contain the are the leaf cells that contain the pigment pigment ChlorophyllChlorophyll which absorbs sunlight and which absorbs sunlight and converts it to sugar. converts it to sugar.

Also uses and controls transpirationAlso uses and controls transpirationCuticleCuticle-- waxy outer surface of leaf, minimizes waxy outer surface of leaf, minimizes drying out of leafdrying out of leafStomataStomata-- small openings on leaf surface that small openings on leaf surface that control the loss of water vapor and exchange gasescontrol the loss of water vapor and exchange gasesGuard cellsGuard cells-- regulate opening and closing of regulate opening and closing of stomata in response to environmentstomata in response to environment

Guard Cells

Vascular Tissue

Cuticle

Chloroplasts

Chlorophyll

Stomata

PhotosynthesisPhotosynthesis

Combines carbon dioxide and water in a Combines carbon dioxide and water in a reaction driven by light to produce sugars reaction driven by light to produce sugars ((carbohydratescarbohydrates or or photosynthatesphotosynthates))Oxygen byproductOxygen byproductOccurs within the Occurs within the chloroplastschloroplastsCarbon dioxide is absorbed and oxygen is Carbon dioxide is absorbed and oxygen is released through released through stomatastomata

RespirationRespirationRespirationRespiration: the process of converting food into : the process of converting food into energyenergyIn trees, stored photosynthates are broken down to In trees, stored photosynthates are broken down to release energy, carbon dioxide and water. release energy, carbon dioxide and water. Energy used for all biological functionsEnergy used for all biological functionsIf respiration is greater than photosynthesis the tree If respiration is greater than photosynthesis the tree must rely on stored energy reservesmust rely on stored energy reserves

Defoliation Defoliation --> Stored energy is used at a higher rate> Stored energy is used at a higher rate

Requires oxygen Requires oxygen Flooding Flooding –– respiration replaces photosynthesisrespiration replaces photosynthesis

QuizQuiz1. The ________ ________ regulate gas 1. The ________ ________ regulate gas

exchange through the stomata. exchange through the stomata. 2. This physiologic feature protects a tree from water loss and pathogen entry after leaf drop.

3. _____________ converts sunlight into stored energy and ____________ releases this stored energy to support biological processes.

Guard Cells

Abscission ZonePhotosynthesis

Respiration

TranspirationTranspiration

Loss of water from the tree primary through the Loss of water from the tree primary through the leaf surfaces (stomata), with minor support from leaf surfaces (stomata), with minor support from the lenticels. the lenticels. Cools the leaves and creates a transpirational pull Cools the leaves and creates a transpirational pull that moves water through xylem and powers that moves water through xylem and powers movement of materials through a tree. movement of materials through a tree. Temperature, humidity, and available water affect Temperature, humidity, and available water affect the rate of transpiration, as well as the type of the rate of transpiration, as well as the type of plantplant

AntitranspirantsAntitranspirantsSprays arborists sometimes use to Sprays arborists sometimes use to close pores, reducing water loss. close pores, reducing water loss. Commonly used during transplant Commonly used during transplant or drought. or drought. Also reduces evaporative cooling Also reduces evaporative cooling of leaves, uptake of carbon of leaves, uptake of carbon dioxide, and rate of dioxide, and rate of photosynthesis.photosynthesis.Can result in tree stress or death if Can result in tree stress or death if misused misused --> decreased > decreased photosynthesis, decreased photosynthesis, decreased evaporative cooling, increased use evaporative cooling, increased use of energy reservesof energy reserves

Internal TransportInternal Transport

OsmosisOsmosis-- water moves from high to low water moves from high to low concentration regions, thus water moves into concentration regions, thus water moves into roots from surrounding soil. roots from surrounding soil.

Water will move out of roots if the water potential Water will move out of roots if the water potential is lower in the soil (i.e.: high salt concentrations in is lower in the soil (i.e.: high salt concentrations in the soil)the soil)

Radial TransportRadial Transport-- movement of water or movement of water or nutrients within the tree between cells of nutrients within the tree between cells of different ages, primarily through ray cellsdifferent ages, primarily through ray cells

Sources and SinksSources and SinksSources – are areas of the tree (i.e. leaves) that produce more energy than they use.

Sinks – areas of the tree that use more energy than they produce.

Food is stored locally first; only surpluses are relocated.

Source

Sink

Photosynthate

Plant Growth RegulatorsPlant Growth RegulatorsGrowth RegulatorsGrowth Regulators-- naturally occurring naturally occurring compounds that act in small quantities to regulate compounds that act in small quantities to regulate plant growth and development. plant growth and development. 5 Primary Growth Regulators5 Primary Growth Regulators

AuxinAuxin-- plant growth hormone, produced in shoot tips plant growth hormone, produced in shoot tips and is important in root development, transported via and is important in root development, transported via living cells. living cells. CytokininCytokinin-- produced in roots, important for shoot produced in roots, important for shoot initiation and growth, transported in water. initiation and growth, transported in water. EthyleneEthyleneAbscic AcidAbscic AcidGibberellinsGibberellins

Growth FormsGrowth Forms

Excurrent Tree Decurrent Tree

TropismTropism

Directional of growth in Directional of growth in response to an external response to an external stimulus. stimulus. GeotropismGeotropism-- response response to gravityto gravityPhototropismPhototropism-- growth growth at an angle toward at an angle toward sunlight. The most sunlight. The most common cause for a tree common cause for a tree lean. lean.

QuizQuiz1. This process moves water through the xylem 1. This process moves water through the xylem

and powers the movement of materials through and powers the movement of materials through a tree.a tree.

2. A tree is improving health and storing energy when ______________ exceeds ____________. 3. This growth regulator is produced in the shoots and is responsible for root development. Auxin

Photosynthesis Respiration

Transpiration

A Side Note About PalmsA Side Note About Palms

MonocotsMonocots-- more in common with grasses more in common with grasses No cambium or growth rings of xylem, instead No cambium or growth rings of xylem, instead have vascular bundles of phloem and xylem have vascular bundles of phloem and xylem interspersed within the steminterspersed within the stemRoots lack secondary growth (cambium Roots lack secondary growth (cambium meristems), so diameter does not increase and meristems), so diameter does not increase and roots remain fibrous. roots remain fibrous.

Final ExamFinal Exam1. Sites of rapid cell division in the shoot tips, 1. Sites of rapid cell division in the shoot tips,

root tips, and cambium are called _________. root tips, and cambium are called _________. 2. Trees that lose their leaves in the fall are called __________. Trees that maintain their leaves for more than one year are called _____________. 3. The green pigment that converts sunlight into chemical energy is called ______________. Chlorophyll

Deciduous

Evergreen

Meristems

4. The _________ ___________ is formed when trunk tissue grows around branch tissues.

Branch Collar

Final ExamFinal Exam5. Rounded trees that lack a central leader and are 5. Rounded trees that lack a central leader and are

broader than they are tall are called _________. broader than they are tall are called _________. 6. ____________ is the loss of water vapor through leaves. 7. The ____________ is a layer of meristematic cells located between the xylem and phloem.

Cambium

TranspirationDecurrent

8. The _________ is a waxy covering on a leaf used to reduce water loss.

Cuticle

9. __________ are small openings in the stem used for gas exchange.

Lenticels

Lateral

Bud

Terminal

Bud

Bundle Scar

Node

Internode

Current Year’s Growth

Leaf Scar

Final ExamFinal Exam10. Label the highlighted structures.

Final ExamFinal Exam11. When cutting through a tree, you would pass through (in 11. When cutting through a tree, you would pass through (in

order)order)a. Bark, Cambium, Phloem, Xylema. Bark, Cambium, Phloem, Xylemb. Bark, Phloem, Cambium, Xylemb. Bark, Phloem, Cambium, Xylemc. Bark, Cambium, Xylem, Phloemc. Bark, Cambium, Xylem, Phloemd. Bark, Xylem, Phloem, Cambiumd. Bark, Xylem, Phloem, Cambium

12. Which one of these is not a plant growth regulator? 12. Which one of these is not a plant growth regulator? a. Petiola a. Petiola b. Gibberellins b. Gibberellins c. Auxinc. Auxind. Cytokinind. Cytokinin

Final ExamFinal Exam13. If the terminal bud is removed in pruning13. If the terminal bud is removed in pruning

a. the branch will die backa. the branch will die backb. growth may be stimulated in lateral budsb. growth may be stimulated in lateral budsc. flowering is stimulated to increase fruit productionc. flowering is stimulated to increase fruit productiond. all of the aboved. all of the above

14. Which of these is not a common type of bud? 14. Which of these is not a common type of bud? a. Terminala. Terminalb. Initiating b. Initiating c. Lateralc. Laterald. Adventitiousd. Adventitious

Guard Cells

Vascular Tissue

Cuticle

Chloroplasts

Chlorophyll

Stomata

15. Label the highlighted structures.

Final ExamFinal Exam16. A _____________ is a plant that grows seeds 16. A _____________ is a plant that grows seeds

without a protective covering. without a protective covering. 17. _______ describes a part of the tree that uses more energy than it produces. 18. The opening and closing of stoma is regulated by _______ _______. Guard Cells

Sink

Gymnosperm

19. The process of _______________ combines CO2 and water in a reaction driven by light.

Photosynthesis

20. Water and dissolved essential minerals are transported in a tree via the _________. Xylem

QuestionsQuestions