The Study of Trees

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Dendrology:

Objectives1. To understand dendrology.

2. To evaluate tree anatomy.

3. To determine the age of a tree.

4. To identify tree species.

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Dendrology • Is the study of plants whose support

system is composed mainly of woody material

• Studies plants including the following:– trees– shrubs– vines

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Trees • Are woody plants with one central trunk• Have a protective covering called bark• Have branches reaching in all directions

from the trunk

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Shrubs• Are plants with

numerous woody stems

• Are usually lower in height than trees

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Vines • Are woody plants which require a

structure for support• Have very flexible stems• Are mostly flowering plants

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Tree Anatomy

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Tree Anatomy • Includes the following major

parts:–leaves–trunk–branches–roots

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Leaves • Are normally green• Are flattened, lateral structures

attached to a stem • Function as the primary organ of

photosynthesis and transpiration in most plants

• Take in oxygen through openings called stomata

• Are protected from dehydration through the external waxy layer

• Adapt to the environment with hairs, bristles, scales or other modifications

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Trunk & Branches • Include a protective layer called

the bark• Include the following functions:

– support– protection from injury and

decay– transportation of liquids– storage of starch and other

minerals10

Bark • Consists of the following two

zones:–inner bark–outer bark

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Inner Bark • Is also known as phloem• Contains tubular cells which distribute

sugars and growth regulators from the leaves and buds to other parts of the tree

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Outer Bark • Consists of layers of inner bark which have

died and been pushed out by the growth of the tree

• Is the tree’s first line of defense to disease caused by insects and bacteria or damage by humans, heat and cold

• Contains a meristematic region

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Meristematic Regions • Are the areas where new cells are formed

which allow the tree to grow• Are located in the following places:

– root tips– buds at the end of twigs– the area between the bark and wood

known as the vascular cambium zone• strongest defense against decay• covers up minor wounds• blocks off and rids entire columns of

rot-infected wood

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Trunk & Branches • Contain the xylem

– which is also known as wood– includes the following types of cells:

• tubular connective cells• ray cells• parenchyma cells

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Tubular Connective Cells

• Run parallel to the trunk or branch

• Carry water and minerals up from the roots

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Ray Cells • Distribute food to living cells• Are sheets of cells in the wood• Are tubes which run from the

inner bark to the center of the tree

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Parenchyma Cells

• Store starch crystals which have the following functions:– are the main raw material for

the fungicides produced by trees in response to injury

– are the main source of energy for growth after injury

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Trunk & Branches • Contain the following:

– heartwood• is located in the center• is involved in the storage

and transport of energy• cannot respond to injury

– sapwood• as it ages, becomes the

toxic waste dump• gives the tree its natural

resistance to decay

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Trunk & Branches– pith

• is a spongy, foam-like material• is the main tissue formed as a twig

grows in length• is eventually covered by wood

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Branches • Are grown through the following process:

– starts at the auxiliary buds found at the leaf joint

– reproducing cells contained in the meristem, located at the tip of the bud, divide and become a twig

– cells located just under the bark divide and the twig grows in diameter, producing a branch

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Roots • Provide the following functions:

– uptake of water, minerals and oxygen– transport of water and minerals to the

trunk of the tree– tree support

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Roots • Take in water and minerals from the soil through

the root hairs called one-celled projections • Carry water to the trunk through conducting roots• Provide support through lateral brace roots

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Tree FactA large tree can have over 30 miles

of roots and five million root tips.

Estimating the Age of a Tree

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Estimating the Age of a Tree

• Includes the following steps:– measure the circumference of the tree– determine the diameter and radius of the tree– adjust for the width of the bark– determine the width of annual rings– determine the estimated age

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Tree Circumference • Is the measurement of the outside of a

tree trunk• Is measured 4.5 feet above the ground

with a measuring tape

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Measuring Tree Diameter

• Diameter– is the measurement of the thickness

or width of the trunk– is determined by the following

equation:• diameter = circumference/pi• pi = 3.14

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Measuring Tree Radius

• Radius– is the measurement of the exact

center of the trunk to the outside edge

– is determined by the following equation:• radius = diameter/2

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Adjusting Width of the Bark

• Subtract 0.5 inches from the radius of thinly barked trees

• Subtract 1 inch from the radius of a tree with thick bark

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Width of Annual Rings

• Can vary between trees due to the following:– genetics– climatic conditions– water and nutrient availability– disease – height– age

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Determining Width of Annual Rings

• Is calculated by performing the following steps:– measure the radius using a cross section of a tree

of similar species– count the number of annual rings within the radius– divide the radius by the number of annual rings

• width = radius/number of annual rings– the result is the average width of one annual ring

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Determining the Estimated Age

• Is calculated by the following equation:– radius/average width of annual

ring = estimated tree age

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Taxonomy

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Taxonomy• Was first used by Carl Linnaeus

in the 1700s• Uses a system of binomial

nomenclature– scientific names consists of

the genus and specie name– the genus name is capitalized,

the specie name is lowercase and both are italicized

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Binomial nomenclature:The scientific naming of species in which each organism is given two

names

Taxonomy • Includes the following classifications

in order from largest to smallest:– kingdom– division– class– order– family– genus– species

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Taxonomy Pneumonic device:

King David Came Over For Green Spaghetti

i i l r a g p

n v a d m e e

g i s e i n c

d s s r l u i

o i y s e

m o s

n

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Dichotomous Keys

• Are tools which aid in determining the identity of living things

• Always consists of two choices in each step– user is asked a pair of

questions– each question is designed to

divide into smaller groups until there is only one left 37

Dichotomous Key Example

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1. a. wings covered by an exoskeleton…………………. ….…..go to step 2

b. wings not covered by an exoskeleton………………...……….go to step 3

2. a. body has round shape……………...…………………..lady bug

b. body has elongated shape………..…...…….…………..grasshopper

3. a. wings point out from the side of the body………………………………...…..dragonfly

b. wings point to the posterior of the body…………………………….………..horsefly

Dichotomous Tree Key

• Identifies the tree by calculating the differences and similarities

• First separates the tree based on whether it is coniferous or deciduous– coniferous: possesses

cones– deciduous: sheds its leaves

each year

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Dichotomous Tree Key

• Then separates the tree based on the following properties:– leaf arrangement– leaf type – leaf shape– leaf margins– leaf tips– leaf bases– leaf vein types 40

Leaf Arrangement

41opposite

alternate

whorled

Leaf Type:Simple

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bipinnate

pinnate

palmate

Leaf Type:Compound

Leaf Shape

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linear

lanceolate

ovatecordate

obovate

Leaf Margins

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entire

crenate

dentate

sinuate

serrate

lobed

Leaf Tips

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Acute

Acuminate

Cuspidate

Obtuse

Truncate

Caudate

Aristate

Mucronate Retuse

Emarginate

Leaf Bases

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Acute Cuneate Rounded

Sagittate Hastate Truncate

Cordate Heart-shaped Oblique

Leaf Vein Types

48parallel

pinnate

palmate

Dichotomous Tree Key

• Then divides the tree based on the presence of twigs and buds

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Dichotomous Tree Key

• Fourth, divides the tree based on the presence of fruit

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Dichotomous Tree Key

• Includes, but is not limited to, the following characteristics:– bark– tree shape– habitat found where growing

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Summary• Dendrology involves the study of woody

plants including trees, shrubs and vines.• Tree anatomy consists of leaves, trunks,

branches and roots.• The estimated age of a tree is calculated

through the equation: estimated tree age = radius/average width of annual ring

• A dichotomous key identifies tree species in order to place a tree in a taxonomy classification. 52

Assessment1. Define dendrology.

2. Name the three types of woody plants.

3. ________ _________ is the home of the younger trees.

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Assessment4. Name the major parts of a tree.

5. Leaves take in oxygen through openings called buds.

a. true

b. false

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Assessment6. Name a function of bark.

7. Name the two leaf types.

8. Name a function of roots.

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Assessment9. Taxonomy was first used by Carl

Linnaeus.

a. true

b. false

10. Name the taxonomy classifications from largest to smallest.

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References • www.ci.huntsville.al.us• www.campgradyspruce.org • www.scarborough.k12.me.us• nerds.unl.edu• www.delawareenvirothin.org/Dendrology

Acknowledgements

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