Question of the Day:
How can you tell one tree from
another? What characteristics
do you use to identify a tree?
Dendrology
 What
is dendrology?
 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
2 Major Tree Divisions

Deciduous





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.
Tree Identification

Trees may be identified by various means
including:
Leaves
 Bark
 Tree Shape
 Flowers and Fruit
 Etc.


Let’s focus on leaves
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?

Leaf Parts

Important Vocab:
Blade = whole leaf
 Petiole = stem
 Margin = outer edge

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.
Simple
Source: Ohio State University– Biology of Horticulture Website
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
Compound Leaves (Cont.)
 Pinnately
Compound
 The
leaflets are
attached across from
each other
 Resembles a
“feather”
 Ex: White Ash
P
I
N
N
A
T
E
Source: Ohio State University– Biology of Horticulture Website
Compound Leaves (Cont.)

Bipinnately or Twice
Compound
 The primary leaflets
are divided into
secondary leaflets,
also written 2-pinnate
 Ex:
Honeylocust
Bipinnate
Source: Ohio State University–
Biology of Horticulture
Website
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

P
A
L
M
A
T
E
Source: Ohio State University– Biology of Horticulture Website
Quick Check for Understanding:
Simple? Compound?
Leaves– How arranged on
twig? (Leaf Arrangement)

Opposite


Alternate


When leaves are arranged directly across from
each other on the twig.
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)
Leaf Arrangement
(Continued)
Alternate
Whorled
Opposite
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.
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.
Quick Check for Understanding:
Alternate? Opposite? Whorled?
A
B
C
Leaves– Margins
 The
margin of the leaf is the leaf
edge.
 3 major types:
 Entire Margin
 Lobed Margin
 Toothed Margin
Leaves– Margins (Cont.)

Entire Margin = smooth edges
Ex:
Eastern
Redbud
Leaves– Margins (Cont.)

Lobed margin = projections that shape the
edge of the leaf
Ex: White
Oak
Leaves– Margins (Cont.)

Toothed Margin = saw-like edge on the leaf

Serrated edge
Example:
Sycamore
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.

Leaves– Veins (Cont.)
Pinnate Veins (Ex: Dogwood)
Leaves– Veins (Cont.)

Palmate Veins (Ex: Sweetgum)

Conifers
Conifers bear cones and have needles.
 Needles
can be single & flat, blunt, round
or sharp.
Spruce needles are
sharp and
individually
attached to the
stem.
 Needles
can be grouped together in tufts or
bundles.
Pine needles are attached to
twig in “bundles” of 3-5,
depending on species