Leaf Collection
7th Grade Science
Plants
The Plant Body: Leaves

FUNCTION OF LEAVES
 Leaves are the solar
energy and CO2
collectors of plants.
 In some plants, leaves
have become adapted for
specialized functions.
EXTERNAL ANATOMY

Leaves possess a blade or lamina, an edge called the
margin of the leaf, the veins (vascular bundles), a
petiole, and two appendages at the base of the petiole
called the stipules.
EXTERNAL ANATOMY
Leaf types – Simple & Compound

Simple leaf =
undivided blade with
a single axillary bud
at the base of its
petiole.

Compound leaf =
blade divided into
leaflets, leaflets lack
an axillary bud but
each compound leaf
has a single bud at
the base of its petiole
pinnately-compound
leaves: leaflets in pairs
and attached along a
central rachis; examples
include ash, walnut,
pecan, and rose.
palmately-compound
leaves: leaflets attached
at the same point at the
end of the petiole;
examples of plants with
this leaf type include
buckeye, horse chestnut,
hemp, and shamrock.
Pinna means feather, so pinnate
leaf resembles a feather.
Deciduous

Now you have to decide if you have a simple
or compound leaf.
Simple Leaves
or
Compound Leaves
Leaf types – Pinnately & Palmately Compound
Leaves
Deciduous

Next you need to look at the leaf’s veins.
Palmate Veins
or
Pinnate Veins
Venation = arrangement of veins in a leaf

Netted-venation = one or a few prominent midveins from which
smaller minor veins branch into a meshed network; common to
dicots and some nonflowering plants.
 Pinnately-veined leaves = main vein called midrib with
secondary veins branching from it (e.g., elm).

Palmately-veined leaves = veins radiate out of base of blade
(e.g., maple).

Parallel venation = characteristics of many monocots (e.g., grasses, cereal
grains); veins are parallel to one another.

Dichotomous venation = no midrib or large veins; rather individual veins have
a tendency to fork evenly from the base of the the blade to the opposite margin,
creating a fan-shaped leaf (e.g., Gingko).
Venation Types
Netted or Reticulate
Venation
Deciduous


Now determine if your leaves are lobed or not
lobed.
Lobed
or
Not Lobed
Kind of edge (margin) on the leaf
Deciduous

By now you may already have your leaf
identified. If not you will need to keep going.
The next few slides will point out some other
unique characteristics of trees and leaves that
make them easy to identify.
Unique Tree
Here are some ginkgo leaves.
They look like they would be
deciduous but they are
actually classified as a type of
gymnosperm. Does anyone
one know why that may be?
Deciduous

Is your leaf toothed or smooth?
Toothed
or
Smooth
Deciduous

What shape does your leaf look like?
Have the petiole towards you. Look at 3 parts of the blade. Top-Middle –Bottom
Ask these questions:
Where is the widest section?
Does the leaf at the petiole start narrow and get wide gradually?
Does it start wide and get narrow gradually?
Does it start narrow, get widet in the middle then get more narrow?
Deciduous

Sometimes deciduous leaves are very narrow.
Willows
Russian-Olive
Leaf Tip Types
Leaf – Internal Anatomy
Internal and External Views
Time to Review
Pinnate Veins

Review Palmate Veins
What type of veins do these leaves have?

Are these leaves lobed or not lobed?
Lobed
Not lobed
These are what lobed leaves look
like:

Do these leave have a toothed or smooth edge?
Smooth
Toothed
Toothed leaves would look like this:
Classifying YOUR leaves
Next class you will classify each of your 10 selected leaves
by these characteristics:
1. Simple or compound
2. Pinnate or Palmate
3. Shape
4. Type of edge or margin
5. Type of tip
Today you will begin to color in the Internal
Structure of a leaf.
1. Do the reading.
2. Answer the questions
3. Color as directed.