1. 7th Grade Science Plants
Leaf Collection
7th Grade Science
Plants

2. 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.

3. 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.

4. EXTERNAL ANATOMY

5. 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

6. 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.

8. Deciduous
Now you have to decide if you have a simple or compound leaf.
Simple Leaves or Compound Leaves

9. Leaf types – Pinnately & Palmately Compound Leaves

10. Deciduous Next you need to look at the leaf’s veins.
Palmate Veins or Pinnate Veins

11. 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).  

12. Venation Types
Netted or Reticulate Venation

13. Deciduous Now determine if your leaves are lobed or not lobed.

14. Kind of edge (margin) on the leaf

15. 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?

16. Deciduous
Is your leaf toothed or smooth?
Toothed or Smooth

17. 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?

18. Deciduous Sometimes deciduous leaves are very narrow.
Willows Russian-Olive

19. Leaf Tip Types

20. Leaf – Internal Anatomy

21. Internal and External Views

22. Time to Review

23. Review Pinnate Veins Palmate Veins
What type of veins do these leaves have?

24. Are these leaves lobed or not lobed?

25. These are what lobed leaves look like:

26. Do these leave have a toothed or smooth edge?

27. Toothed leaves would look like this:

28. Classifying YOUR leaves
Next class you will classify each of your 10 selected leaves by these characteristics:
Simple or compound
Pinnate or Palmate
Shape
Type of edge or margin
Type of tip
Today you will begin to color in the Internal Structure of a leaf.
Do the reading.
Answer the questions
Color as directed.