Dendrology

Dendrology

• The study of dendrology includes tree:• Identification• Characteristics• Taxonomy• Ecology

Trees Can be Placed into Two Different Categories

• Gymnosperms• Seeds are naked• Most species retain leaves, except bald

cypress • Leaves are needle or scale like

• Angiosperms• Leaves are broad and flat• Over 200,000 species• Can be divided into monocots and dicots

Gymnosperms

• Gymnosperm — literally means “naked” “seed”. Therefore there is NO fruit

• Examples:– Cycads– Pines

Gymnosperms

• Gymnosperms have male & female parts

Angiosperms

Angiosperm — literally means “vessel seed”flowering plants, who’s seeds are enclosed in fruit.

Examples: • Fruit trees: apple,

cherry, plumb, orange

• Most deciduous trees: birch, maple, oak, dogwood

• Flowering plants

Angiosperms• Angiosperms have to undergo a

process called pollination before they can reproduce.

• Stamen – male sex organs. On the end of the stamen is the anther which makes pollen The pollen has to be taken to the

• Pistil – female part of the flower. The pollen is left on the stigma and is then carried down a tube called the style to the ovary.

• Some plants can cross pollinate. This means they can pollinate themselves. Others rely on pollinators.

Gymnosperm or Angiosperm?

LEAF ARRANGEMENTSAlternate leaves are arranged singly and are usually arranged in a spiral pattern alongthe stem. Alternate leaves are sometimes placed along just two sides of the stem

Opposite leaves are borne in pairs, the members of which are positioned on opposite sides of the stem. A common pattern for opposite leaves is for each successive set of paired leaves to be rotated 90 degrees.

Whorled leaves When three or moreleaves are positioned at a node, they are considered to be whorled.

Types of leavesSimple- One leaf per stem/auxillary bud

Palmately compound- many leaves per stem radiating out like the palm of your hand

Pinnately compound- many leaves per stem. Leaflets are on one main stem.

TEST TIME!

(2)

Simple or Compound?

Alternate or Opposite?

Simple or Compound?

Alternate, Opposite or Whirled?

Entire - smooth, no bumps

Serrate - pointing to the leaf's tip

Leaf Margins

Lobed - deep indents or sinuses

Double serrated- two teeth on one

What are the Leaf Edge Characteristics?

Leaf VenationThe lines that appear on the surface of a leaf and look like blood vessels are called veins

The two main types are:

Pinnately- One main vein going up the middle

Palmately- Lots of veins starting at the base and radiating outward like the palm of your hand and your fingers

How to use a dichotomous key:“Dichotomous” means “divided into two parts.” That is why dichotomous keys give two choices (sometimes three) in each step. In each step, you are presented with two statements based on characteristics of the organism. If you make the correct choice every time, the name of the organism will be revealed at the end.

So here is your first tree to key out. You will need to look at the all of the following to help you. The branch, the leaf buds, and one leaf.

Read the first TWO steps, which one describes the tree/leaf.

• 1. Leaves Broad (Mostly common deciduous trees)……………………………………………………………………….2

• 1. Leaves needle-like or scale-like (Mostly evergreens, native or introduced)……………………….26

YOU MUST WRITE DOWN EVERY STEP YOU TAKE!

Your leaf is a broad leaf so go to step number 2.

Now read Both Number 2’s

• 2. Stems limber or flexible, running along the ground, or may be climbing on trees or other objects by means of aerial roots or tendrils with adhesive disks…………………….3

• 2. Stems not lying along the ground; upright ………………..5If your plant is a VINE then go to number 3. If it is a tree go to 5

So far so should have written down 1,2,5

Go to the number 5’s• 5. Leaf veins dichotomously (forked), fanlike

…………………………………..…………………… GINKGO BILOBA

• 5. Leaves not dichotomously veined.…………………….….6

Does your leaf look like this? If not go to number 6

Your leaf

Look at the branch

6. Leaves opposite or whorled……….7

6. Leaves alternate.………………...….8

Yes, leaves are opposite so goto number 7

How do you tell if leaves are opposite or alternate?

Look at the leaf buds

• 7. Leaves whorled, usually three to a node. Leaves very large and broad, margin smooth and unlobed ….

7. Leaves opposite………………………..9

So far you should have steps 1,2,5,6,7,9

What does whorled mean again?

At least three leaves that go around the branch at the same location.

So, your leaf is opposite, because there are only two leaves.

Your branch

• 9. Leaves Compound………………..10

• 9. Leaves Simple……………………….11

So, how can you tell? Find one leaf. You canTell one leaf by following the stem to the bud.If there are many leaflets on one leaf, it is compound.

So this leaf is compound many leaflets on one leaf.

• 10. Leaves pinnately compound: 5-7 leaflets; ………………………………….. GREEN ASH. (Fraxinus pennsylvanica)

• 10. Leaves pinnately compound: 9-21 leaflets; green fruit 1-11/2 inches in length…BLACK WALNUT(Juglands nigra)

You should have this written down 1,2,5,6,7,9,10, Green Ash (Fraxinus pennsylvanica)

So here is your first tree to key out. You will need to look at the all of the following to help you. The branch, the leaf buds, and one leaf.

• 1. Leaves broad (Mostly common deciduous trees)………………………………………………………………….2

• 1. Leaves needle-like or scale like (Mostly evergreens, native or introduced)………...….26

Now read Both Number 2’s

• 2. Stems limber or flexible, running along the ground, or may be climbing on trees or other objects by means of aerial roots or tendrils with adhesive disks…………………….3

• 2. Stems not lying along the ground; upright ………………..5If your plant is a VINE then go to number 3. If it is a tree go to 5

So far so should have written down 1,2,5

Go to the number 5’s• 5. Leaf veins dichotomously (forked), fanlike

…………………………………..…………………… GINKGO BILOBA

• 5. Leaves not dichotomously veined.…………………….….6

Does your leaf look like this? If not go to number 6

Look at the branch

6. Leaves opposite or whorled……….7

6. Leaves alternate.………......………...….8

8. Leaves compound. …........128. Leaves simple…………….…..14

14. Leaves entire, smooth margin.…………15

14. Leaves not entire shaped (lobed) or has serrated edges.……………………………….18

18. Leaves ovate, 5 to 6 inches long, with serrate margins, base is unequally cordate, green above and paler below……………….American Basswood (Tilia americana)

18. Leaves star shaped, bark of twigs corky. ….........................................Sweet Gum (Liquidambar styraciflua )

18. Leaves not star shaped…………………………………………………....19

19. Leaves tulip shaped; truncate…............ Yellow Poplar (Liriodendron tulipifera)

19. Leaves triangle shaped, serrate edges, and has a flat petiole …………………………...............................….……Cottonwood (Populus deltoids)

19. Leaves not tulip or triangle shaped.………………………………20

Yes, I would call this tulip shaped.

Liriodendron tulipifera (Tulip Tree) - The characteristics of this species are unique. The leaves are lobed. The strangely shaped leaves resemble no other plant. The flowers look a bit like a tulip and are green and orange (two strange colors for a flower). Recently, the tree has been used in toxic dumps, to clean the area. It absorbs many heavy metals such as lead and mercury at no evident cost to the tree. This is a massive tree - native to parts of the Eastern U.S.

So you should have written down 1,2,5,6,8,14,18,19 Yellow Poplar

Now do this one by yourself.

Yes these leaves are all from the same tree.