1. Question of the Day:
How can you tell one tree from another? What characteristics do you use to identify a tree?

2. Dendrology What is dendrology? Trees vs. Shrubs
Dendrology is the scientific study of trees and other woody plants.
Trees vs. Shrubs
Tree = one, main woody stem
Shrub = small, woody, branched
from base

3. 2 Major Tree Divisions Deciduous Conifers aka: Hardwoods & Broadleaf
Sheds leaves seasonally
Broad leaves
Hardwood
Examples: Oaks, Maples, Tulip Poplars, etc.
Conifers
aka: Softwoods & Evergreen
Bear cones
Needle or scale-like leaves
Softwood
Examples: Pines, Cedars, Firs, etc.

4. Tree Identification
Trees may be identified by various means including:
Leaves
Bark
Tree Shape
Flowers and Fruit
Etc.
Let’s focus on leaves

5. Leaves Leaves are often the easiest/best way to identify a tree.
Needles and scale of evergreens are also considered leaves.
Some questions to consider when identifying leaves:
Simple or compound?
Margins smooth or rough?
Arrangement on twig opposite or alternate?
Veins pinnate (like a feather) or palmate?

6. Leaf Parts Important Vocab: Blade = whole leaf Petiole = stem
Margin = outer edge

7. Leaves– Simple or Compound
Simple leaves only have one leaf blade.
Compound leaves are made up of several separate leaflets attached to a common leaf stem.

8. Simple
Source: Ohio State University– Biology of Horticulture Website

9. Compound Leaves Important to remember:
Compound leaves have leaflets which are attached to the leaf stalk (not the twig)
Leaflets can be attached to the leaf stalk in several ways:
Pinnately Compound
Bipinnately Compound
Palmately Compound

10. Compound Leaves (Cont.)
Pinnately Compound
The leaflets are attached across from each other
Resembles a “feather”
Ex: White Ash

11. P I N N A T E
Source: Ohio State University– Biology of Horticulture Website

12. Compound Leaves (Cont.)
Bipinnately or Twice Compound
The primary leaflets are divided into secondary leaflets, also written 2-pinnate
Ex: Honeylocust

13. Bipinnate
Source: Ohio State University– Biology of Horticulture Website

14. Compound Leaves (Cont.)
Palmately Compound
The leaflets are arranged in a pattern that looks like fingers on the palm of a hand
Ex: Horse Chestnut

15. P A L M A T E
Source: Ohio State University– Biology of Horticulture Website

16. Quick Check for Understanding: Simple? Compound?

17. Leaves– How arranged on twig? (Leaf Arrangement)
Opposite
When leaves are arranged directly across from each other on the twig.
Alternate
When leaves stagger up the twig and are NOT located directly across from each other.
Whorled
2 or 3 leaves attached at the same point on the twig and “whorl” around the twig (think of circle)

18. Leaf Arrangement (Continued)
Alternate
Whorled
Opposite

19. Leaf Arrangement (Cont.)
Most trees have alternate branching.
Think to yourself “MAD Horse” (Maple, Ash, Dogwood, and Horse Chestnut) to remember those with opposite branching.

20. Leaf Arrangement (Continued)
It is important to remember…
The opposite vs. alternate vs. whorled arrangement refers to the way the LEAVES are arranged on TWIG, not the way the leaflets are arranged on the leaf stalk.

21. Quick Check for Understanding: Alternate? Opposite? Whorled?B A C

22. Leaves– Margins The margin of the leaf is the leaf edge.
3 major types:
Entire Margin
Lobed Margin
Toothed Margin

23. Leaves– Margins (Cont.)
Entire Margin = smooth edges
Ex:
Eastern
Redbud

24. Leaves– Margins (Cont.)
Lobed margin = projections that shape the
edge of the leaf
Ex: White
Oak

25. Leaves– Margins (Cont.)
Toothed Margin = saw-like edge on the leaf
Serrated edge
Example:
Sycamore

26. Leaves– Veins Pinnately veined means that there is only one main vein.
Palmately veined means that there are several main veins originating from the petiole.

27. Leaves– Veins (Cont.)
Pinnate Veins (Ex: Dogwood)

28. Leaves– Veins (Cont.)
Palmate Veins (Ex: Sweetgum)

29. Spruce needles are sharp and individually attached to the stem.
Conifers
Conifers bear cones and have needles.
Needles can be single & flat, blunt, round or sharp.
Needles can be grouped together in tufts or bundles.
Spruce needles are sharp and individually attached to the stem.
Pine needles are attached to twig in “bundles” of 3-5, depending on species