Tree identification

1
IDENTIFYING
PENNSYLVANIA TREES

Tree Identification
In this presentation you will learn to identify trees
using the Summer Key to Pennsylvania Trees.
Trees can be identified
using many factors
including leaves, bark,
twigs, buds, flowers,
and fruits.
Let’s review some
terminology used to
describe these.

The Summer Key
Available for free download
from PSU Outreach at:
ecosystems.psu.edu/youth/sftrc
/lesson-plan-pdfs/summer-key
Note: If you have an older copy of the Key, dated before 2002,
there are three mistakes. (Look for date at the bottom right of the
last page of the key.)
• 6b should read: “Needles without stalks,” rather than
“Needles with stalks.”
• 33b should read: “Leaves rough or hairy,” rather than “Leaves
rough and hairy.”
• 40a should read: “Terminal leaflet usually larger than other
leaflets,” rather than “Terminal leaflet much larger than other
leaflets.”

Scale-like
thin, flat and closely appressed
to the branchlets, as in the
arborvitae or Northern white-cedar.
Note: This illustration shows
several leaves.

Broad and flat
Characteristic of many
deciduous species.

Needles
needles can be sharp as in pines
and spruces, or more blunt as in
Eastern hemlock.

Leaf-type Comparison
Scale-like Broad and flat Needles

9
LEAF ARRANGEMENT
It all starts here….

Opposite-leaved
Two leaves attach to the stem directly across
from each other.
The buds are at the junction of the leaf and
twig.

Alternate-leaved
The points of attachment of
the petioles (leaf stalks) are
staggered along the stem.
Petioles do not attach to the
stem directly across from each
other.
The bud is at the junction of
the twig & leaf petiole. These
buds will remain after leaves
drop, helping you recognize the
leaf arrangement (alternate,
opposite, or whorled).

Whorled leaves
There are three or more leaves attached at the
same point along the stem.

Leaf Arrangement Comparison
Alternate
Opposite
Whorled

Petiole (leaf stalk)
Bud
Simple leaf
Not divided into leaflets (which we’ll see shortly).
The bud that occurs along the stem where the leaf
attaches indicates whether the leaf is simple or
compound. (In a compound leaf, there is no bud at
the base of the individual leaflets.)

Leaflet
Bud
Pinnately compound
Compound Leaf
A leaf that is divided into leaflets.
Notice there is only one bud here:
thus, only one leaf with seven leaflets.
This figure is pinnately compound;
having leaflets arranged on opposite
sides of an elongated axis.
Note: The bud actually occurs along
the twig, near where the leaf stalk
attaches, and not on the leaf stalk
itself.

Compound Leaf
Leaflet
Bud
Palmately compound
This is an example of a
palmately compound leaf;
leaflets all attach near a
common point, resembling the
fingers of a hand.
Note: There is only one bud
here; thus, there are five leaflets
that make up one leaf.

Leaf Structure Comparison
Simple leaf Pinnately compound
leaf
Palmately compound
leaf

Leaf Margins
The edges (or “margins”) of the leaf are also used in identification.
No teeth
or lobes
Sharp teeth
pointing
directly out
Sharp teeth
pointing
forward
Each sharp
forward-pointing
tooth has
smaller teeth
Large,
rounded
projections
(like an ear
lobe!)

20
IDENTIFICATION
Let’s practice tree ID using the Summer Key

21
NEEDLES
A group of trees that is easiest to identify
by looking at the leaf type – a needle.

Hint: needles single on twigs
Key Guide:
• 1a – leaves needle or scale-like
• 2b – leaves needle
• 4a – needles (leaves) single on twigs
• 5a – needles flat, blunt
• 6a – needles with small stalks (attaches
needles to twig)
= Hemlock
Eastern Hemlock
Tsuga canadensis

Eastern Hemlock
Tsuga canadensis
Leaves: Evergreen needles occur
singly, appearing two-ranked on
twigs, flattened, about ½” long, dark
green and glossy above, light green
with two white lines below.
Twigs: Slender, tough, yellowish-brown
to grayish-brown. Buds egg-shaped,
1/16” long, reddish-brown.

Eastern Hemlock
Fruit: Cones ¾” long, egg-shaped,
hanging singly from the tips of the twigs.
Under each scale are two small, winged
seeds.
Bark: Flaky on young trees, gray-brown
to red-brown; thick and roughly grooved
when older.

Eastern Hemlock
General: Eastern hemlock is the
official state tree of Pennsylvania.
A large, long-lived tree, used for
construction and as a source of tannic
acid for tanning leather. Found in
cool, moist woods throughout the
commonwealth. Ruffed grouse, wild
turkey, and songbirds find food and
shelter in this tree. Deer browse it
heavily when deep snow makes other
foods scarce.
Sadly, the Hemlock Wooly Adelgid is killing
off most of the trees in the state and has
been nearly impossible to stop.

Similar to the first ‘needle’ example,
with one major difference
Hint: needles without stalks
Key Guide:
• 4a – needles (leaves) single on twigs
• 5a – needles flat, blunt
• 6b – needles without stalks
= Fir
Balsam fir
Abies balsamea

Balsam Fir
Abies balsamea
Leaves: Evergreen; 1-1 ½” long.
Spreading almost at right angles in
two rows on hairy twigs; curved
upward on upper twigs; flat, with
rounded tip. Shiny, dark green
above, with two-narrow, whitish
bands beneath.
Twigs: Twigs smooth or nearly
smooth

Balsam Fir
Fruit: Cones 2-3 ¼” long;
cylindrical; green tinged &
dark purple; upright on
topmost twigs. Scales finely
hairy, bracts mostly short and
hidden; paired long-winged
seeds.
Bark: Brown, thin, smooth,
with many resin blisters,
becoming scaly.

Balsam Fir
General: The only fir native to the
Northeast, with narrow, pointed,
spire-like crown of branches and
aromatic foliage. Generally grows
40-60’. A major pulpwood species.
Also used for interior knotty pine
paneling. Christmas trees, wreaths,
and pillows utilize the sweet
smelling foliage. Deer browse in
winter.

Hint: study the needle shape
Key Guide:
• 4a – needles (leaves) single on
twigs
• 5b – needles four-sided and
sharp-pointed
= Spruce
Norway spruce
Picea abies

Norway Spruce
Picea abies
Leaves: Evergreen, stiff, ½ to 1”
long. Needles are 4-angled but
somewhat flattened, with a
sharp-pointed tip, shiny green.
Twig: Slender to medium in
size, lacking hair, orange-ish
brown. Needles are borne on
woody pegs.

Norway Spruce
Fruit: Cones are very large,
cylindrical, 4 to 6 inches long,
with stiff scales that are
irregularly toothed. Turning
brown and maturing September
to November.
Bark: Red-brown and scaly, later
turning gray with flaking scales
or plates.
Flower: Males yellow-brown in
large groups; females upright,
purple.

Norway Spruce
General: A European species
that has become a valuable
naturalized member of our
forests, and extensively planted
as an ornamental. A large tree
with a dense conical crown.
Branchlets on older trees
droop. Wood used chiefly for
paper pulp, boxes, crates, and
lumber.

Balsam Fir Norway
Spruce
Comparing firs and spruces
• Twigs smooth or nearly
smooth
• Twigs roughened by
peg-like leaf bases that
remain on the twigs
after the needles fall
• Needles softer, flattened, and
usually bluntly rounded at tip
(“Firs are friendly.”) • Needles stiff, four-sided,
pointed at tip
Two differences are
twigs and needles

Hint: number of needles
Key Guide:
• 4b – needles (leaves) in
bundles, tufts, or rosettes
• 7a – needles in bundles with
sheath at base
• 8a – needles in bundles of five
= Pine
Eastern white pine
Pinus strobus

Eastern White Pine
Pinus strobus
Leaves: Evergreen needles in
clusters of five; soft & flexible; 3-
sided, 2 ½ -5” long, and bluish-green.
This is the only pine native
to Pennsylvania with five needles
per bundle.
Twigs: Slender, flexible, with rusty
hairs when young, later smooth.
Buds egg-shaped, usually less than
½” long, gray-brown.

Eastern White Pine
Fruit: Cones 5”-8” long, without
prickles, slightly curved, resinous;
each scale usually bears two
winged seeds (as do all our native
pines).
Bark: Young trunks and branches
greenish-brown, later darker,
grooved, and scaly.

Eastern White Pine
General: Eastern white pines are large
trees. At present they usually reach
50- 90’ high. “Penn’s Woods” once saw
white pines reaching 150’ and more. It
is one of the most valuable softwood
timber trees, found in moist or dry
woodlands throughout the state, and
often planted as an ornamental in
large open areas.
Many types of wildlife feed on the
seeds and soft needles. The inner bark
is the preferred winter food of the
porcupine; deer browse the twigs.

And another pine, in a different bundle:
Key Guide:
• 4b – needles (leaves) in bundles, tufts,
= Red pine
Red Pine ID Slide
or rosettes
• 7a – needles in bundles with sheath at
base
• 8b – needles not in bundles of five
• 9b – needles in bundles of two
• 10a – needles about 4 inches long
• 11b – needles stiff, snap apart when
bent
Red pine
Pinus resinosa

Red Pine
Pinus resinosa
clusters of two, slender, 4”-6” long,
dark green, borne in dense tufts at
the ends of branchlets; snap easily
when bent double.
Twigs: Stout, ridged, yellow-brown
to red-brown, buds egg-shaped,
about ½” long, brown at first and
later silvery.

Red Pine
Fruit: A glossy brown cone,
about 2” long, without
prickles, nearly stalkless,
remains attached until the
following year.
Bark: Notably reddish-brown
along entire length.

Red Pine
General: Like the white pine, this medium-to-large
tree develops one horizontal whorl of
side branches each year. A valuable softwood
timber tree in the northern part of the State,
its wood is used chiefly for construction.
Native on dry slopes in Luzerne, Wyoming,
Tioga, and Centre counties and planted
extensively by the Bureau of Forestry and the
Pennsylvania Game Commission. Songbirds,
mice and chipmunks feed on the seeds.
In some areas, a tiny insect is killing these
trees. The red pine scale can destroy entire
stands within a year or two.

And another pine…bundles of three
Key Guide:
• 4b – needles (leaves) in
bundles, tufts, or rosettes
• 7a – needles in bundles with
sheath at base
• 8b – needles not in bundles of
five
• 9a – needles in bundles of
three
= Pitch pine
Pitch pine
Pinus rigida

Pitch Pine
Pinus rigida
clusters of three (and, rarely,
in clusters of two); stiff, 2” –
5” long, yellowish-green.
Twigs: Stout, brittle, rough,
angled in cross-section,
golden-brown. Buds egg-shaped,
about ½” long,
resinous, red-brown.

Pitch Pine
Fruit: Cones 1” – 3” long with
short, stiff prickles, nearly
stalkless, often remains
attached for five years or
more after ripening. Many
remain unopened until
heated by passing forest fire.
Bark: Green and smooth on
young branches; thick, rough,
and grayish-brown on older
trunks.

Pitch Pine
General: Pitch pine is a medium sized
tree, 40’-50’ high. Widespread in PA,
except the northwestern counties. It is
more common on poor, sandy soils and
areas where forest fires have killed most
other trees. Its wood has a high resin
content, and is used for railroad ties,
construction lumber, pulpwood, and fuel.
Pitch pine seeds are important to
nuthatches, pine grosbeaks and black-capped
chickadees. Deer and rabbits
browse the seedlings.

Hint: needles in tufts
Key Guide:
• 4b – needles (leaves) in bundles,
tufts, or rosettes
• 7b – needles in tufts or rosettes
= Larch
American larch
Larix laricina

American Larch
Larix laricina
Leaves: Needles not evergreen;
occur singly near the ends of
the twigs, elsewhere in clusters
of ten or more; about 1” long,
pale green, turning yellow and
falling from the tree during the
autumn.
Twigs: At first covered with a
bluish-white coating, becoming
dull brown and with numerous
short spurs. Buds round, small,
1/16” long, dark red.

American Larch
Fruit: A cone, about one
inch long, egg-shaped,
upright, often remains
attached for several years
after ripening in the fall.
Bark: Smooth at first,
later becoming scaly,
dark brown.

American Larch
General: A medium-sized tree also
known as Eastern larch and
Tamarack. Only cone-bearing tree
native to PA that loses its needles
annually. Found locally in moist
situations. Wood used chiefly for
paper pulp, lumber, posts, and
railroad ties..
[European larch (L. decidua) and Japanese larch (L. leptolepis) are more
commonly planted in the State.]

Hint: scale-like needles
Key Guide:
• 2a – leaves scale-like
• 3a – scales pointed, twigs
not flat
= Redcedar
Eastern Redcedar
Juniperus virginiana
And note that
“redcedar” is
correct – a
single word!)

Eastern Redcedar
Juniperus virginiana
Leaves: Mature are evergreen;
opposite, in four rows forming
slender, four-angled twigs; 1/16” to
1/8” long on leaders. Scale like, not
toothed, dark green with gland dot.
Leaves on younger branches are
needlelike, 1/2” long, yellow-green to
blue-green, and sharp.

Eastern Redcedar
Fruit: 1/4 -3/8” in diameter;
berrylike; dark blue with a
white bloom; soft, juicy,
sweetish, and resinous; 1-2
seeds.
Bark: reddish-brown; thin,
fibrous, and shreddy.

Eastern Redcedar
General: evergreen, aromatic
tree growing 40 – 60’ in height
with a diameter of 1 -2’. Lives in
dry uplands, especially
limestone, and open fields,
woods, and fence rows; often in
scattered pure stands.

55
OPPOSITE LEAVES
For non-needle leaves, trees are best identified
by separating them into two groups, based on
the leaf arrangement.

Key Guide:
• 1b – leaves broad and flat
• 12a – leaves opposite or
whorled on stem
• 13a – leaves opposite
• 14a – leaves simple
• 15b – margins lobed
= maple
Red Maple
Acer rubrum

Red Maple
Acer rubrum
Leaves: Opposite, simple,
with 3-5 shallow lobes,
coarsely toothed, light
green above, pale green to
whitish beneath, turning
brilliant red or orange in
autumn.
Twigs: Slender, glossy; at
first green, later red to
reddish-brown.

Red Maple
Fruit: Wings usually less than 1”
long, spreading at a narrow
angle, red to brown, maturing
in May or June.
Bark: Smooth and light gray on
young trunks and branches;
older trunks darker, shaggy, and
roughened with long irregular
peeling flakes.

Red Maple
General: Found throughout PA in a wide variety of habitats, typically
reaching 50’ high, sometimes over 100’. It grows best in wet soils.
Also known as ‘soft maple’ because its wood is not as hard as sugar
maple. Young trees are heavily browsed by deer and rabbits, with
rodents consuming the seeds.

Here’s another maple,
with the same key ID….
Key Guide:
whorled on stem
Unlike the red maple, with its coarse teeth,
this maple has only a few large teeth
Sugar maple
Acer saccharum

Sugar Maple
Acer saccharum
Leaves: Opposite, simple, 5-lobed
with a few large teeth, about 4”
wide, bright green above, pale
green below. Leaves turn bright
yellow, orange, or red in autumn.
Twigs: Reddish brown to light
brown. Buds brown and sharp-pointed.

Sugar Maple
Fruit: Horseshoe-shaped
with wings almost
parallel, maturing in
autumn, sometimes
persisting into winter.
Bark: Gray-brown,
smooth on young trunks,
older trunks fissured with
long, irregular flakes.

Sugar Maple
General: Also called ‘rock
maple’ for its hard wood,
this important timber tree
is found on moist wooded
slopes throughout PA,
reaching heights of 60’-80’.
The wood is used for
furniture, musical
instruments and flooring,
and the sap is collected for
maple syrup production.
Birds and rodents eat the seeds. Deer,
squirrels, porcupine and other mammals
browse the twigs, buds, and bark.

And maple number 3:
Key Guide:
whorled on stem
Norway maple
Acer platanoides
Like the sugar maple, this maple
has five deep lobes, though this
leaf has sharper angles between
the lobes.

Norway Maple
Acer platanoides
Leaf: Opposite, simple, and palmately-veined,
5 to 7 lobed with long-pointed
"teeth,“ dark green above, paler below.
The best way to tell this part from a sugar
maple is that this leaf exudes milky white
sap from the petiole when detached.
Twig: Stout, reddish-brown. Buds glossy
red with green at the base, bud scales
with keel-like ridges. Leaf scars meet to
form a sharp angle, encircling the twig.

Norway Maple
Fruit: Widely divergent 2-
winged samaras, spreading
nearly to the horizon. 1 1/2 to 2
inches long in clusters,
relatively flat seed cavity,
mature in autumn.
Bark: Smooth and light brown
on young trees, dark and
fissured but not scaly when
older.

Norway Maple
General: Imported from
northern Europe and
extensively planted along city
streets and in parks. Typically
reaches 50’ high. An invasive, it
frequently escapes from
cultivation to grow in disturbed
woods and roadways. Can be
distinguished from other
maples by the larger leaves,
milky sap of the petiole, and
the horizontal wings of the
fruit.

And finally, maple number 4:
Key Guide:
whorled on stem
Striped maple
Acer pensylvanicum
This maple has a simpler profile
than the other ones we’ve seen.

Striped Maple
Acer pensylvanicum
Leaves: Opposite, simple,
three-lobed, rounded at the
base, with finely-toothed
margins.
Twigs: Smooth and stout, at
first greenish, later red. The
pith is brown with each
season’s growth marked by two
or three dark lines encircling
the twig.

Striped Maple
Fruit: Wings very divergent, about
¾” long, maturing in September in
drooping clusters. Marked on one
side of the seed with a
depression.
Bark: Smooth and greenish or
reddish-brown, conspicuously
marked with longitudinal white
streaks (a.k.a., “snakebark”).
Older trunks are rougher, darker
and less streaked.

Striped Maple
General: Usually from 10’-25’
high; common in the
mountainous parts of the
state on moist, cool, shaded
slopes and in deep ravines.
This is the largest of the
world’s ‘snakebark’ maples (all
with those vertical stripes on
the bark), and the only one
not native to Japan or China.

Let’s compare the maple leaves:
Sharp lobe
divisions;
larger
Sugar Norway Red Striped
Rounded
between lobes
Rounded
base
Coarsely-toothed

Moving on from the maples, let’s look at a different leaf
shape. Hint: look at the margins of the leaf
Key Guide:
We start off the same…
whorled on stem
But then look at this:
• 15a – margins entire
= Dogwood
Flowering dogwood
Cornus florida

Flowering Dogwood
Cornus florida
Leaves: Opposite, simple, 3”-5” long;
clustered towards tips of twigs; margins
smooth or wavy; veins prominent and
curved like a bow. Foliage bright red in
autumn.
Twigs: Red tinged with green, often with a
bluish white waxy coating; marked with
rings; tips curve upward. End leaf bud
covered by two reddish scales; side leaf
buds very small, flower buds conspicuous,
silvery, turban-shaped, at ends of twigs.

Flowering Dogwood
Fruit: An egg-shaped
drupe, ½” to 3/5” long; coat
red; flesh yellowish: stone
grooved, two-celled;
usually in clusters of 2-5;
persist after the leaves fall.
Flowers: greenish white or
yellowish, small, in flat-topped
clusters; four showy
white bracts underneath;
open before the leaves.

Flowering Dogwood
General: A lovely ornamental tree that
has been heavily hybridized for use in
gardens, dogwood still appears in its
wild form in PA forests.
Unfortunately, a widespread fungus
threatens many of these trees.

Let’s try a compound leaf. Hint: pinnately* compound
Key Guide:
whorled on stem
• 13a – leaves opposite on
stem
• 14b – leaves compound (leaf
made up of leaflets)
• 16a – pinnately-compound
• 17b – leaf divide into seven
leaflets
= Ash
* opposite
White ash
Fraxinus americana

White Ash
Fraxinus americana
Leaves: Opposite; compound; about 10” long;
with five to nine leaflets, each 3” to 5” long,
short stalked, silvery beneath, margins entire
or with a few rounded teeth toward the tip.
Twigs: Stout, usually smooth, gray-brown with a
few pale lenticels and a white, waxy coating
which is easily rubbed off (called a bloom.) Buds
rusty to dark brown, blunt with adjoining leaf
scars half-circular and notched at the top. The
first pair of lateral buds usually at the base of the
end bud causing a terminal enlargement of the
twig.

White Ash
Fruit: A winged seed, called a samara,
usually 1” – 2” long and ¼” wide,
shaped like a canoe paddle with a
rounded tip and hanging in clusters
which remain attached for several
months after ripening in autumn.
Bark: Gray-brown, evenly furrowed into
diamond shaped areas separated by
narrow interlacing ridges, slightly scaly
on very old trees.

White Ash
General: A large tree, often up to 80’ or
more; usually with a long-straight trunk
commonly found on rich soils. The
wood is used for sporting goods
(especially baseball bats), handles,
agricultural tools, and furniture. The
juice from the leaf has been reported to
relieve mosquito bite itching. Fall foliage
ranges from brilliant yellow to dark
maroon.
The Emerald Ash Borer has been killing
many trees throughout the state. It can
be identified by a ‘D’-shaped exit hole in
the bark.

81
ALTERNATE LEAVES
And now for leaves arranged in an
alternate pattern.

This next example has a lot of steps. Hint: fine teeth
= Cherry
Key Guide:
• 12b – leaves alternate on stem
• 19b – margins deeply cut, lobed, or
toothed
• 22b – margins coarsely or finely toothed
• 28b – teeth fine, several for each main
lateral vein
• 30b – leaves broad
• 31b – leaves about twice as long as broad
• 33a – leaves smooth, single serrate, fine
teeth
• 34a – leaf stalk with one or two glands
(small bumps on stem); has a sour odor
when twig is broken
Black cherry
Prunus serotina

Black Cherry
Prunus serotina
Leaves: Alternate, simple, 2-5” long; narrow
with tapering tip, shiny above, paler below
and usually with one or more small glands at
the base; margins with short in-curved teeth
which distinguish it from other cherries.
Twigs: Smooth, reddish-brown, marked with
numerous pale, round lenticles; often
covered with a thin gray coating which rubs
off easily. Buds smooth, shiny, sharp
pointed, reddish-brown tinged with green.
When broken, very bitter smelling.

Black Cherry
Fruit: Round, black with a purplish
tint; 1/3-1/2” in diameter,
containing a single, round, stony
seed. Arranged in hanging clusters.
Flowers: white, blooms in June.
Bark: Smooth and shiny, with
transverse markings (lenticels) when
young. Bark becomes dark, blocky
and breaks up when mature.

Black Cherry
General: Commonly 50-70’
high, this species grows
throughout the state. It
thrives in fertile alluvial soil,
but also grows well on dry
slopes. The hard reddish-brown
wood is highly prized
for quality furniture and
interior trim.
Many game birds, song
birds, and mammals,
including black bear, eat the
fruit and seeds.

This one has even MORE steps! Hint: leaves rough
Key Guide:
toothed
lateral vein
• 31b – leaves about twice as long as
broad
• 33b – leaves rough or hairy
• 35a – rough leaves
• 36a – leaf margins double-serrate from
base, pinnately veined
= Elm
American elm
Ulmus americana

American Elm
Ulmus americana
Leaves: alternate, simple, 4”-6”
long, unequal at the base, rather
rough at the upper surface; usually
soft-hairy below; veins prominent;
margin coarsely toothed. Petiole
short.
Twigs: slender, zigzag, brown,
slightly hairy. Leaf buds 1/8”- ¼”
long, flattened. Flower buds larger,
below leaf buds. Bud scales red-brown,
smooth or downy; margins
dark.

American Elm
Fruit: a seed surrounded by an
oval, thin papery wing, 1/2” long,
deeply notched at the tip; ripening
in spring and borne in clusters;
wing with scattered hairs along
margin. Flowers and fruit appear
before the leaves, as is true of
Slippery elm.
Bark: Dark gray to gray-brown with
long corky ridges; separated by
diamond-shaped fissures on older
trees.

American Elm
General: a large and highly prized
shade tree. The drooping crown
often gives it a vase-shaped
appearance. Found locally
throughout Pennsylvania, mainly on
moist areas. The hard, tough wood
has many uses, including the
manufacture of boxes, barrels, and
furniture.
It has been severely affected by a
fungus, Dutch Elm Disease, and a
bacteria, Elm Yellows, which have
killed off many of the trees in North
America.

Now let’s examine some compound leaves.
Hint: sap not milky; leaves hairy
= Black Walnut
Key Guide:
• 39b – sap not milky
• 40b – terminal leaflet as large or
smaller than other leaflets, or it
may be lacking
• 41b – leaflet pointed
• 42b – leaves hairy
• 44b – terminal leaflet small or
lacking
Black walnut
Juglans nigra

Black Walnut
Juglans nigra
Leaves: Compound, alternate; leaflets 15 to
23, each 3”-4” long, small-toothed; dark
yellow-green above, paler, hairy below. End
leaflet absent or very small. Main leaf-stem
with very fine hairs.
Twigs: Stout, orange-brown to dark brown,
roughened by large leaf scars, easily broken,
leaving U-shaped scars; pith pale brown,
chambered. Buds gray, downy; side buds 1/6”
long, end bud larger.

Black Walnut
Fruit: a round nut, 1”-2” in
diameter, shell rough, covered
with a thick, almost smooth,
green spongy husk; oily kernel
sweet.
Flower: in drooping green
catkins, appearing with the
unfolding leaves, which is also
true of butternut.
Bark: dark brown to gray-black,
with narrow ridges.

Black Walnut
General: a large-sized tree,
found locally on rich soils
mainly in the southern part of
the State. Wood valuable for
quality furniture, veneer, gun
stocks and musical
instruments.

Another compound leaf. Hint: study the terminal leaflet
Key Guide:
• 1b – leaves broad and
flat
• 12b – leaves alternate
on stem
• 18b – leaves
compound (leaf made
up of leaflets)
• 40a – terminal leaflet
usually larger than
other leaflets*
= Hickory
* Though this is not always true
Bitternut hickory
Carya cordiformis

Bitternut Hickory
Carya cordiformis
Leaves: Alternate, compound, 6-10”
long, divided into 7-11 lance-shaped
leaflets, bright green and smooth
above; paler and slightly downy
beneath, margins finely to coarsely
toothed.
Twigs: Slender, smooth, glossy, orange-brown
to grayish with numerous pale
lenticels. Buds covered by four sulphur-yellow,
gland-dotted outer scales. End
buds flattened, ¾” long.

Bitternut Hickory
Fruit: Nearly round, almost heart-shaped,
with a prominent point at
tip. ¾”-1 ½” in diameter with a
thin, yellowish gland-dotted husk,
which splits into four sections
almost to the middle when ripe.
The ridgeless, reddish-brown to
gray-brown nut has a thin shell
protecting a bitter kernel.
Bark: The tight gray bark remains
rather smooth for many years,
eventually developing shallow
furrows and low, narrow
interlacing ridges.

Bitternut Hickory
General: Related to the walnut,
bitternut hickory, by contrast,
has a nut so bitter that both
animals and humans avoid it.
Growing to heights of 70-100’, it
is found throughout the eastern
US.

Let’s look at a third compound leaf example, this time with
rounded leaves
Key Guide:
• 12b – leaves alternate on
stem
• 40b – terminal leaflet as large
or smaller than other leaflets,
or it may be lacking
• 41a – leaflet round-tipped
= Black Locust
Black locust
Robinia pseudoacacia

Black Locust
Robinia pseudoacacia
Leaves: Alternate,
compound, 7-19 oval
leaflets 1”-2” long, margins
smooth.
Twigs: Angled, somewhat
zigzag, brittle, with short-stout
prickles; no end bud,
side buds small and hidden
in winter.

Black Locust
Fruit: A thin, flat pod, 2”-4”
long; usually with 4-8 seeds;
splits into halves when ripe.
Flowers: white, showy, and
very fragrant in drooping
clusters, appearing in May and
June.
Bark: Reddish-brown, rough,
furrowed, and thick.

Black Locust
General: A medium-sized tree to
45’ high, found in open woods,
floodplains, thickets and
fencerows throughout the state.
Wood is durable when in contact
with soil and in demand for posts,
poles, railroad ties, and mine
timbers. Several insects and wood
rots cause heavy damage,
especially to trees on poor soils.
Squirrels eat the seeds, and bees
make honey from the nectar of
locust flowers.

This leaf looks sort of like a maple, but it isn’t related
Key Guide:
• 12b – leaves alternate on
stem
• 19b – margins deeply cut,
lobed, or toothed
• 23a – leaves with five
deeply cut lobes, star-shaped
leaf
= Sweet Gum
Sweetgum
Liquidambar styraciflua

Sweetgum
Liquidambar styraciflua
Leaves: Star-shaped or maple-like,
3”-6” long. Has five to seven pointed
lobes with finely saw-toothed
margins. Has a resinous odor when
crushed. Shiny and dark green
above, turning a reddish color in the
fall.
Twigs: Green to brown, and stout.
Some branches can have cork-like
growths.

Sweetgum
Fruit: A long-stalked drooping
brown ball 1-1 ¼” long,
containing many individual fruits.
Each with 1-2 long-winged seeds,
maturing in autumn and often
persisting into winter.
Bark: Gray; deeply furrowed into
narrow scaly ridges.

Sweetgum
General: Also known as Redgum
or Sapgum, a large aromatic tree
with a straight trunk and conical
crown that becomes round and
spreading, 60-100’ tall. It is an
important timber tree used for
cabinetwork, veneer, plywood,
pulpwood, barrels, and boxes.
Grows well in moist soils of
valleys and lower slopes. Often a
‘pioneer’ after logging and in old
fields.

This next example has lobed leaves (also similar to the
maples), but the leaves alternate on the stem.
Key Guide:
toothed
• 22a – margins deeply cut or lobed
• 23b – leaves not star-shaped
• 24b – leaves not square or notched
• 25b – leaves with more than two lobes
• 26a – leaf veins pinnate
• 27b – lobes sharp-pointed with a hair-like
bristle on end of each lobe
= Red Oak
Northern red oak
Quercus rubra

Northern Red Oak
Quercus rubra
Leaves: Alternate, simple, 4”-9” long, to 6”
wide, with 7-11 bristle-tipped lobes, sinuses
between lobes extend half-way to the mid
rib. Smooth, dull green above, paler with
small tufts of reddish-brown hair in vein-axils
(i.e., where the side veins join the mid-rib)
beneath.
Twigs: Greenish-brown to reddish-brown,
smooth when mature. Buds
pointed, light brown, smooth.

Northern Red Oak
Fruit: An acorn, ¾” to 1 ¼” long;
the cup shallow, saucer shaped,
covering ¼ of the nut, cup-scales
reddish-brown, narrow, tight,
sometimes fuzzy on the edges. The
acorns ripen in two growing
seasons; the kernel is bitter.
Bark: Smooth and greenish-brown
or grey, maturing to dark grey or
nearly black and is divided into
rounded ridges.

Northern Red Oak
General: A dominant forest tree
throughout the state growing up
to 90’ in moist to dry soils.
Deer, bear, and many other
mammals and birds eat the
acorns.
The hard, strong wood is used for
furniture, flooring, millwork,
railroad ties and veneer. The red
oak group includes all oaks with
bristle-tipped leaves and acorns
that ripen over two seasons.

Another oak….
Key Guide:
White Oak ID Slide
toothed
• 25b – leaves with more than two lobes
• 26a – leaf veins pinnate
…and finally, we see the difference!
• 27a– lobes rounded
= White Oak
White oak
Quercus alba

White Oak
Quercus alba
Leaves: alternate, simple, 6”-9”
long, and 4” wide, with 6-10
rounded lobes; bright green
above, paler below, both
surfaces smooth on mature
leaves.
Twigs: red-grey, often with a
grayish coating. Buds rounded,
reddish-brown, smooth, to
1/8” long; end buds clustered.

White Oak
Fruit: an acorn, about 1”
long, light brown, cup bowl
like, hairy inside, enclosing
25% of the nut; cup scales
warty at the base. Acorns
ripen in one season in
September.
Bark: Pale grey, scaly, not
deeply fissured, often flaky

White Oak
General: a dominant forest tree on
dry to moist sites, occurring
throughout the state, usually
reaching 80’-100’ high. This tree is
very important to both wildlife and
people. The acorn is an important
food for animals. Eastern Native
Americans made a flour from
them. Commercial uses include
flooring, whiskey barrels and boat
building. The “white oak group”
includes all oaks without bristle-tipped
lobes and acorns that ripen
in one season.
The famous Revolutionary
War frigate USS Constitution,
“Old Ironsides,” was made of
White oak.

White Oak Red Oak
Notice the difference between
the rounded lobes of the
White oak compared to the
pointed lobes of the Red oak.
Acorn – notice the White oak
cup more bowl-like as
compared to the Red oak
being more saucer-like.
White oak acorns mature in
one season, while Red oak
acorns take two seasons to
mature.

Now let’s study some
margins and teeth.
Key Guide:
• 19b – margins deeply cut,
lobed, or toothed
• 22b – margins coarsely or
finely toothed
• 28a – teeth coarse, one at end
of each lateral vein
• 29b – leaves not more than
two times as long as wide
= Beech
American beech
Fagus grandifolia

American Beech
Fagus grandifolia
Leaves: alternate, simple, 3-4” long,
stiff leathery texture, with a tapered
tip and sharply-toothed margins,
light green and glossy above, yellow-green
below.
Twigs: slender; dark yellow to gray;
at first hairy, later smooth; zigzag.
Buds very long, slender, sharp
pointed, and covered by 10 – 20
reddish-brown scales.

American Beech
Fruit: a stalked, prickly
4-valved bur
containing triangular,
pale-brown, shining
nuts.
Bark: smooth, light
gray, mottled with
dark spots.

American Beech
General: found on moist, rich soils
throughout its range; more abundant
in the north. An important timber
species typically reaching 50 – 60’
high, but can grow taller. Beechnuts
are a very important source of food
for wildlife including bears, squirrels,
and grouse; however, species
produces good crops infrequently,
every five to seven years. Beech is a
handsome shade tree for large open
areas in parks and golf courses.
Beech leaves often persist into winter.

And this leaf, by contrast, has finer teeth.
Key Guide:
toothed
lateral vein
• 35b – soft, hairy leaves
• 37a – leaf margins double-serrate, base
blunt to slightly heart-shaped, some
aromatic
= Birch
Yellow birch
Betula
alleghaniensis

Yellow Birch
Betula alleghaniensis
Leaves: Alternate, simple, 3”-4”
long, doubly-toothed margins, dull-green
above, yellow-green beneath.
Twigs: Green and hairy when young
later brown and smooth, with only a
faint wintergreen flavor and smell.
Buds dull yellowish green, slightly
downy.

Yellow Birch
Fruit: An erect, very short-stalked
cone, 1 ½” long, made
up of small, winged nuts and
scales.
Bark: Young stems and branches
yellowish or bronze and shiny,
peeling off in thin papery strips.
Older trunks becoming reddish-brown
and breaking into large,
ragged-edged plates.

Yellow Birch
General: A medium to large tree,
usually 60’-75’, occasionally to 100’.
Prefers moist, cool soils and cool
summer temperatures, often found on
north-facing slopes and swamps. The
wood is used for cabinets, furniture,
flooring, and doors. It was a principal
wood used for distilling alcohol, tar,
and oils. Ruffed grouse feed on buds
and seeds, deer and rabbits browse
the twigs.

Another birch:
Key Guide:
Sweet (Black) Birch ID Slide
toothed
lateral vein
aromatic
Sweet birch
(Black birch)
Betula lenta

Sweet (Black) Birch
Betula lenta
Leaves: alternate, simple, about 3 ½”
long, unevenly saw-toothed, dull
green above, yellow-green beneath
with some white hairs where the veins
join the midrib. The leaf base is usually
heart-shaped.
Twigs: green and somewhat downy
when young, becoming reddish-brown,
smooth and shiny. They have a
strong wintergreen flavor and smell.
Buds reddish-brown, conical, sharp-pointed
and shiny.

Sweet (Black) Birch
Fruit: a very small, winged nut. As in
other birches, nuts together with
small scales, form a cone-like
structure, about 1 ½” long.
Bark: tight, dark reddish-brown on
younger trees, marked with horizontal
lines of pale lenticles and often
resembles the bark of young Black
cherry. On older trees the bark breaks
into large black plates.

Sweet (Black) Birch
General: Also known as Black birch or
Cherry birch, this tree normally attains
heights of 50’ to 60’, and is found on a
variety of sites from rich fertile lowlands
to rocky ridges throughout the state. The
heavy, hard, strong wood is used for
furniture, boxes, and fuel-wood.
Distillation of the bark and twigs
produces an oil of wintergreen.
Fermented sap can be used to make
birch beer. Ruffed grouse feed on buds
and seeds; deer and rabbits browse the
twigs.
This tree, in NY, measures 130”
around at chest height!

And a third birch:
Key Guide:
toothed
lateral vein
aromatic
Paper birch
Betula
papyrifera

Paper Birch
Betula papyrifera
Leaves: alternate, simple,
2-3” long, 1 ½” – 2” wide,
upper surface dark green,
lower surface light green,
narrowed or rounded at
the base, sharply-toothed
margins and sharp-pointed
tip.
Twigs: at first greenish and
hairy, later becoming
smooth reddish-brown.

Paper Birch
Fruit: a cylindrical, short-stalked
strobile about 1 ½”
long. The seeds are small and
winged.
Bark: trunk and older branches
chalky to creamy white,
marked with horizontal stripes
and peeling off in thin layers.
Older trunks rough and often
fissured into irregular thick
scales.

Paper Birch
General: a large tree, 50 – 70’
tall on upland woods and
slopes in north-central and
northeastern PA. Seeds and
buds are eaten by the state
bird, the Ruffed grouse. Twigs
are browsed by deer. Native
Americans used the bark for
constructing canoes, shelters
and containers.

131
UNIQUE CHARACTERISTICS
Some trees have special features (unusual leaves,
fruits, or bark) that make them easy to identify.

Memorable Palmate Leaf
Key Guide:
whorled on stem
• 13a – leaves opposite on
stem
• 14b – leaves compound
(leaf made up of leaflets)
• 16b – palmately compound
= Horse Chestnut
Horse Chestnut ID Slide
Horse chestnut
Aesculus hippocastanum

Horse Chestnut
Aesculus
hippocastanum
Leaves: opposite, palmately
compound, with leaf stalks 3-7”
long. Usually 7-9 leaflets,
(sometimes five); saw-toothed.
Dull, dark green above, paler
beneath.
Twigs: light brown; stout; hairless;
ending in large, blackish, sticky
bud.

Horse Chestnut
Fruit: Maturing in late summer; a
brown spiny capsule, 2-2 ½” in
diameter, splitting into two to three
parts; 1-2 brown poisonous seeds.
Flower: 1” long, white with red or
yellow markings, fringed petals.
Appear in 6-12” high clusters.
Bark: Gray or brown; thin and
smooth, becoming fissured and
scaley.

Horse Chestnut
General: NOT a true chestnut
(its name derives from the fact
that some people confused its
fruits with that of real
chestnuts). An introduced
shade tree with spreading,
rounded crown of stout
branches and course foliage.
The horse chestnut is a shade
and street tree that likes rich,
moist soils. It is easily
propagated from seed and
tolerant of city conditions.

Another distinctive leaf
Hint: look at the lobes
Key Guide:
toothed
• 25a – leaves from same tree may be
entire, or with one or two lobes; aromatic
= Sassafras
Sassafras
albidum

Sassafras
Sassafras albidum
Leaves: Alternate, simple 4”-6” long,
smooth, dark green above, much
lighter beneath, characteristically
aromatic when crushed. Usually three
types can be found on a tree: entire,
two-lobed and three-lobed (rarely
five-lobed).
Twigs: Bright green, sometimes
reddish, smooth and shiny; large white
pith. End bud much larger than side
ones, with many lose scales.

Sassafras
Fruit: A berry, dark blue,
shiny, about ½” in diameter,
on a red stem enlarged at
the point of attachment;
borne in clusters. Yellow
flowers appear before the
leaves unfold.
Bark: Young trees furrowed,
greenish, changing to
brown; inner bark salmon
colored; older trees show
deep fissures extending
long distances up the trunk.

Sassafras
General: A small to medium-sized
tree, to 50’ high, with crooked
branches; often spreading by root
suckers. Its roots, leaves, twigs and
fruit have a spicy odor; the oil
contained in these parts is used for
a “tea,” in medicines, perfumes, etc.
Wood used chiefly for fuel and
fence posts.

And a third unique leaf
Hint: look at the top of the leaf
Key Guide:
toothed
• 24a – leaves square or notched at
top
= Tulip Poplar
Yellow (Tulip) Poplar
Liriodendron tulipifera

Yellow Poplar
Liriodendron tulipifera
Leaves: Alternate, simple, 4”-6”
in diameter, generally four-lobed,
bright green, turning
yellow in autumn.
Twigs: In spring and summer,
green, sometimes with purplish
tinge; during winter, reddish-brown,
smooth and shiny. Buds
large, smooth, flattened.

Yellow Poplar
Fruit: At first green,
turning light brown
when ripe in autumn;
cone-like, 2 ½” – 3”
long. Made up of
winged seeds. Greenish
yellow tulip-like flowers
in May or June.
Bark: Young trees dark
green and smooth with
whitish vertical streaks.
Older trunks are dark
gray and furrowed.

Yellow Poplar
General: Also known as tulip
poplar, white poplar and
whitewood. A large tree – the
tallest of the eastern
hardwoods. It grows rapidly
and is an important timber
and shade tree. The wood is
valuable for veneer and many
other uses. Songbirds and
game birds, rabbits, squirrels,
and mice feed on the seeds.
Whitetail deer browse the
young growth.
This tree is the second largest in
Washington DC, standing 96’ tall,
with a 120 foot crown.

In this example, it is the fruit that is
unusual, but let’s still start with the leaf.
Key Guide:
• 19a – Margins entire
• 20b – leaf base tapering
• 21b – leaves 5 to 10 inches long, thin
= Cucumber-tree Magnolia
Cucumber-tree magnolia
Magnolia acuminata

Cucumber-tree Magnolia
Magnolia acuminata
Leaves: Alternate, simple, 4”-
12” long, smooth above,
downy beneath; margins
smooth or somewhat wavy.
Twigs: Reddish-brown, shiny,
with peppery smell and taste.
Buds covered with greenish-white
silky hairs; end buds ½”
– ¾” long. Leaf scars
horseshoe-shaped.

Fruit: When young, like a small
green cucumber, when mature
in autumn, 3”-4” long, a
cluster of small red pods, each
containing two scarlet seeds;
often remains attached all
winter. Flowers large (3” long),
greenish-yellow, single,
upright; appear from April to
June.
Bark: Gray-brown to brown,
developing long, narrow
furrows and loose scaly ridges.

General: A medium-sized tree,
native to rich upland woods and
slopes in the western half of the
commonwealth. Magnolia wood is
used mainly for interior finish,
furniture, and containers.
Songbirds, squirrels, and mice eat
the seeds.

This small tree (or large shrub) also has
very distinctive fruit
Key Guide:
• 18b – leaves compound (leaf made
up of leaflets)
• 39a – sap milky (in stems)
= Sumac
Smooth sumac
Rhus glabra

Smooth Sumac
Rhus glabra
Leaf: Alternate, pinnately compound, 11 to
31 leaflets per leaf, leaves are 12 to 18 inches
long. Leaflets are lance-shaped, serrate and
are 2 to 4 inches long. Leaflets are finely
hairy below. Whitish beneath, turning
maroon in the autumn.
Twig: Stout, lacking hairs and often with a
whitish bloom. Buds are small, rounded and
covered with light brown hairs.

Smooth Sumac
Fruit: A drupe borne in clusters.
Fruits are dark red, round and
hairy, 1/8 inch long. Maturing
September to October but often
persisting through winter.
Flower: White petals, borne on
upright clusters up to 8 inches
long. Flowering June to August.
Male and female parts usually
found on separate plants.
Bark: Brown-gray and
smooth, becoming scaly
with age.

Smooth Sumac
General: A shrub or small
tree with a short or multi-stemmed
trunk and
spreading branches. Only
shrub or woody species
native to all lower 48 states.
It is eaten by many types of
wildlife, including birds,
small mammals, and deer.
Indians would eat the young
sprouts as salad, and the
fruit could be chewed to
quench thirst.

And this tree, which is not found in the key, has a
tell-tale bark
Leaves:
• Alternate
• Simple
• 3-5 lobed
• 4”-7” across, generally wider
than long, light green above,
paler and wooly beneath,
petiole hollow at the base,
enclosing next year’s bud.
Sycamore
Platanus occidentalis

American Sycamore
Platanus occidentalis
Leaves: Alternate, simple, 3-5
lobed, 4”-7” across, generally wider
than long, light green above, paler
and wooly beneath, petiole hollow
at the base, enclosing next year’s
bud.
Twig: begin as pale green, coated
with fine hairs, later dark green and
smooth, finally become light gray or
light reddish brown.

Sycamore
Fruit: A round, light-brown ball, 1” in
diameter, made up of many seeds
surrounded by silky hairs, hanging singly
or in pairs by a tough, slender stalk
throughout the winter.
Bark: Consists of two layers, the outer
peeling in brown flakes, the inner whitish,
yellowish or greenish, the base of old
trunks dark brown and fissured. This tree
is easily distinguished from other trees by
this exfoliating bark which flakes off in
great irregular masses, leaving the
surface mottled, and greenish-white, gray
and brown.

Why does the Sycamore bark look like that??
The bark of all trees has to yield to a
growing trunk by stretching, splitting,
or infilling; the sycamore shows the
process more openly than many other
trees. The explanation is found in the
rigid texture of the bark tissue which
lacks the elasticity of the bark of some
other trees, so it is incapable of
stretching to accommodate the growth
of the wood underneath. Instead, the
tree sloughs it off.

Sycamore
General: Large, massive
trees typically found on
stream banks and
floodplains attaining heights
of 70’-125’ or more. Also
called Buttonwood or
American planetree, the
wood is used for furniture,
butcher blocks and flooring.
The London planetree,
(Platanus × acerifolia), with
2-4 fruits per stalk, is
commonly planted as a
shade tree in urban areas.
This sycamore, which has its own park in Lansdowne,
PA, is estimated to be the second largest in the US. It
measures 7.01m (just under 23’) at chest height, and
is about 26.21m (almost 86’) tall. This tree was planted
around the year 1650, which makes it more than 350
years old!

Other Resources
There are many books and filed
guides to help you fine-tune the skills
you’ve learned today.
Several of these are specific to
Pennsylvania trees.

Other Resources
You can also refer to general guides for North
America or the Eastern US.
The National Wildlife Foundation guide has
good ID tips, along with an easy-to-follow
format.
The Peterson is a commonly
used standard.
And the Fandex guides offer
an unusual approach, with
leaf-topped cards to help
quickly compare to field
specimens.

There’s an App for That
And of course there are some great
apps. Some are similar to field guides,
while others use photo comparison
systems and are organized visually.
But a word of caution – apps that
require a connection to the internet
may not always work in the forests!!
• LeafSnap
• vTree (Virginia Tech Tree ID app)
• Arbor Day Tree Identification Guide

References
• Common Trees of Pennsylvania, Department of
Conservation & Natural Resources, Bureau of Forestry
• The Audubon Society Field Guide to North American
Trees Eastern Region, Knolph, Alfred A. Inc. 1980
• Virginia Tech Dendrological Web Page,
www.fw.vt.edu/dendro/dendrology/main.html
•University of Wisconsin, botanical images,
www.wisc.edu/botit/dendrology/names.html

The Summer Key To Pennsylvania Trees is a small
part of the Pennsylvania 4-H forestry curriculum.
Contact your Penn State Cooperative Extension
Office to request additional information about 4-H
and other educational programs.

Prepared by Paul Roth, Research Assistant, and Rance Harmon,
Extension Associate, The Pennsylvania State University, School of
Forest Resources & Cooperative Extension
Acknowledgements
• Idea development and review: Jason Hall, Sandra Insalaco, and Cecile Stelter –
Service Foresters – Pennsylvania Department of Conservation and Natural
Resources, Bureau of Forestry
• Review: James Finley & Sanford Smith, The Pennsylvania State University School
of Forest Resources & Cooperative Extension
• Images provided courtesy of Virginia Tech & The University of Wisconsin.
• Line art courtesy of The Pennsylvania State University College of Agricultural
Sciences and the Pennsylvania 4-H Program

Tree identification

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