Leafy Learning: Identification Characteristics for LeavesKnowing how to describe a leaf can help you identify trees.

Leaf Arrangement

Simple leaves look like one leaf with one blade and one petiole. They can be different shapes but always have only one blade.

Simple CompoundCompound leaves look like they are made up of many leaves, but they are only one leaf. The leaf blade is divided into leaflets. These leaflets look like small leaves. Some leaflets are divided again and so they are made up of subleaflets. These leaves can be different shapes.

Leaf vs LeafletSo how can you tell a leaf from a leaflet? Leaves join onto the tree’s twigs whereas leaflets join onto the leaf ’s midrib. Where a leaf is pulled off a twig, it leaves a leaf scar and you may see a bud. Where a leaflet is pulled off a leaf ’s midrib, there is no bud or large leaf scar.BladeMidrib

Midrib

Petiole

Blade

Leaflet

Subleaflet

Petiole PetioleLeaflet

Leaf

Leaflet

No LeafScar

Twig

Leaf Scar

Bud

Midrib

Midrib

One Leaf One LeafSeven Leaflets

One LeafSix Leaflets

Thirty Subleaflets

a a a

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Leafy Learning: Identification Characteristics for Leaves

Being able to describe the margins of a leaf is important.

Twig Arrangement

Leaf Margins

Margin (edges of the leaf blade) is smooth.

EntireMargin has teeth. The teeth can be fine and small, coarse and large or even doubled.

ToothedMargin is indented and wavy. Lobes can be sharp or rounded.

Lobed

The orientation of the veins, lobes and leaflets. Leaf Venation

Veins, lobes and/or leaflets radiate from one point, like your fingers from your palm.

PalmateVeins, lobes and/or leaflets start in pairs from the midrib of the leaf blade.

Pinnate

How leaves grow along a twig or branch can be very helpful in identification of trees. Most of our trees have leaves that grow in an alternate arrangement from the twig. A few of our trees, such as maples, ashes and dogwoods, grow in an opposite arrangement (local botanists use the first letter of these trees’ names and call this the MAD principle). A rarer type of arrangement is called

whorled. This type has the leaves growing off the twig in bunches of three or more.

Alternate WhorledOpposite

Twigpage 2

Leafy Learning: Identification Characteristics for LeavesThis sheet shows many different types of leaves. Can you understand how each of these leaves got its name?(note: “bi” means “two”)Simple Entire Simple Toothed

Simple PinnatelySharply Lobed

Palmately Compound Pinnately Compound Bipinnately Compound

Simple PinnatelyRounded Lobed

Simple PalmatelyLobed

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Leafy Learning: Identification Characteristics for Leaves

Activity #1 - Test Your Knowledge

Now that you’re a leaf expert, let’s test your skill! Using the “Native Tree Leaves in your Neighbourhood” biodiversity, sort the following leaves into the appropriate columns. Go back to the leaf characteristic sheets if you need help!

Red Maple, Honey Locust, Ohio Buckeye, Staghorn Sumace, Tulip Tree, Kentucky Coffeetree, American Beech

Leaf Arrangement

Simple Bipinnately CompoundPinnately CompoundPalmately Compound

Now, let’s take a look at leaf margins. Using the “Native Tree Leaves in your Neighbourhood” biodiversity sheet, sort the following leaves into the appropriate columns:

Tulip Tree, Sassafras, Elm, Common Hop-Tree, Paw Paw, Black Walnut, Birch

Leaf Margins

Entire CompoundToothedLobed

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Leafy Learning: Identification Characteristics for Leaves

Activity #1 - Test Your Knowledge continued

Now you’re ready for the big test! Can you correctly classify all of these leaves from your “Native Trees in your Neighbourhood” sheet? Kentucky Coffeetree Black Walnut Mountain-Ash Ash Ohio Buckeye Sugar MapleAmerican Sycamore Tulip Tree Red Oak Bur Oak Redbud Largetooth AspenHackberry Ironwood American Beech Hawthorn Dogwood Paw Paw

All Leaf Characteristics

Simple Entire Simple Palmately Rounded Lobed

Simple PalmatelySharply Lobed

Simple Toothed

Simple Palmately Lobed Bipinnately CompoundPinnately CompoundPalmately Compound

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Leafy Learning: Identification Characteristics for Leaves

Activity #2 - Outdoor ResearchOutside Time! Now that you are a trained botanist (someone who studies plants), you can out into your yard and/or neigh-bourhood and look for tree leaves. In general, a tree is a plant with a single, woody, permanent trunk growing out of the ground (there are exceptions, of course). Put a checkmark in the appropriate Leaf Type box for each leaf you find. Also, put a check-mark in one of the three Twig Arrangement boxes. When you are done, look at your data. What do you notice? What is the most common leaf type or the most common twig arrangement? Scientists don’t have perfect answers on why different tree species have differently shaped leaves or twig arrangements. Maybe you can solve the puzzle someday!

Simple Entire Simple Palmately Rounded Lobed

Simple PalmatelySharply Lobed

Simple Toothed

Simple Palmately Lobed Bipinnately CompoundPinnately CompoundPalmately Compound

Alternate WhorledOpposite

Twig Arrangement

Leaf Type

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Leafy Learning: Identification Characteristics for Leaves

Don’t forget the Conifers!Did you know that pine needles are actually leaves? They are just very tough leaves that can live through the winter (though there are exceptions). There are twelve native conifer trees in Ontario. While telling some of the individual species apart can be tricky, knowing the basic groups of conifers is not too difficult.

Pines Red-CedarWhite-CedarTamarack

- needles short and four-sided (they roll in your fingers well)- needles project from all around the twig, making it look like a brush

- needles are two-sided and flat- needles project mostly on sides of the twig, making it look like a feather- needle joins the twig with a ball-shaped swelling

- needles are two-sided and flat- needles project mostly on sides of the twig, making it look like a feather- needle joins the twig with a little stem-like projection

HemlockFirSprucesPines

- long and slender needles in bunches of two, three or five- always check more than one bunch of needles on a tree because sometimes individual needles may be missing from a bunch

- needles in bunches of more than 5- needles very soft and short- needles turn yellow and fall off every autumn

- needles are flattened into small scales- branches of needles soft

- needles are either very sharp and pointed or tiny soft scales - branches of needles often prickly

Red-CedarWhite-CedarTamarack

Activity #3 - Evergreen Eyes Go outside and find some evergreens (another word for conifers). Put a check in each box for each one your find. Which species group is the most common in your area?

Spruces Fir Hemlock

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