USFS AlaskaCommon Trees of Alaska |
Brochure of Common Trees of Alaska. Published by the U.S. Forest Service (USFS).
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Common
Trees of Alaska
United States
Department of
Agriculture
Prepared by
Forest Service
Alaska Region
R10-XX-XXX
August 2009
Mountain hemlock – Tsuga mertensiana
Needles
• Light- to medium-green on top, with two whitish parallel lines beneath, needles are unequal
in length from 1/4 to 7/8 inch long;
• Blunt-tipped, soft, shiny, and flat, generally
growing from two sides of branch parallel to
the ground.
Cones
• Brown, oval-shaped, 5/8 to 1 inch long;
• Thin, papery scales.
Bark
• Reddish-brown when young, turning graybrown;
• Scaly when young, becoming thick and furrowed with age.
Size at maturity and life span
• 100 to 150 feet in height and 2 to 4 feet in
diameter;
• 200 to 500 years.
Habitat and distribution
• Sea level to subalpine areas;
• Along Coast Range in central California to the
Kenai Peninsula of Alaska.
Needles
• Dark green, white lines on both surfaces, moreor-less equal in length, 1/2 to 1 inch long;
• Soft and growing from all sides of the branch in
a bottle brush pattern.
Cones
• Purplish when young, brown when mature;
• Cylindrical, 1 to 2-1/2 inches long;
• Thin, papery scales.
Bark
• Divided into narrow flattened ridges, becoming
thick and deeply furrowed with age;
• Gray when young, turning reddish brown with
age.
Size at maturity and life span
• 50 to 100 feet in height and 10 to 30 inches in
diameter, can be prostrate in alpine;
• Slow-growing trees, size 18 to 20 inches in
diameter at 180 – 260 years;
• 400 to 500 years
Habitat and distribution
• Sea level to 3,500 feet elevation;
• From crest of the Sierra-Nevada in California to
the Kenai Peninsula in Alaska.
Mountain hemlock – Tsuga mertensiana
Western hemlock – Tsuga heterophylla
Western hemlock – Tsuga heterophylla
Alaska yellow-cedar
Cupressus nootkatensis
Needles
• Scalelike shiny yellow-green. 1/16 to 1/8 inch
long;
• Springy, fan-shaped sprays of branches, turning
up at ends;
• Branch sprays flat and symmetrical, bottom
side with white stomate markings.
Cones
• Brown, oval-shaped, 1/2 inch long;
• Clustered near end of branches;
• Cone scales overlap, woody, and curve outward at maturity.
Bark
• Fibrous and stringy;
• Cinnamon-red when young, becoming gray
with age.
Size at maturity and life span
• 70 to 100 feet in height in Southeast Alaska
(growing much taller in southern part of range)
and 2 to 4 feet in diameter (occasionally reaching 6 feet);
• 300 to 700 years (occasionally 1,000).
Habitat and distribution
• Coastal forests;
• Sea level to 500 feet in elevation;
• From northwestern California to Southeast
Alaska just south of Frederick Sound.
Western redcedar – Thuja pilcata
Alaska yellow-cedar – Cupressus nootkatensis
Needles
• Scalelike, overlapping, sharp pointed, 1/16 to
1/8 inch long;
• Yellow-green to deep green;
• Top and bottom of branch sprays similar, without apparent white stomate markings.
Cones
• Spherical about 1/2 inch in diameter;
• Green, maturing to brown in 2 years;
• Made of 4-6 shield-shaped scales, sharp central point on each scale, scales do not overlap.
Bark
• Shredding, grayish brown.
Size at maturity and life span
• Slow-growing trees;
• 40 to 100 feet tall, and 1 to 2 feet in diameter;
• Shrub-sized and contorted in bogs and at tree
line;
• Lives up to 1,500 years.
Habitat and distribution
• Wetland and subalpine forests;
• Sea level to tree line;
• From Oregon north along coast through Prince
William Sound, Alaska.
Western redcedar – Thuja plicata
Sitka Spruce – Picea sitchensis
White spruce – Picea glauca
Alaska’s state tree
Needles
• Dark blue-green, squarish, 5/8 to 1 inch long;
• Needles sharp, growing on all sides of branches from woody pegs, a character common to
spruce.
Cones
• Light orange-brown, 2 to 3-1/2 inches long;
• Usually found in the top quarter of tree, hanging down from branches;
• Papery scales.
Bark
• Thin and smooth when young, developing
scaly plates with age;
• Gray, becoming dark purplish brown with age.
Size at maturity and life span
• 150 to 225 feet in height and 5 to 8 feet in
diameter;
• Grows to larger size in southern part of its
range;
• 500 to 700 years.
Habitat and distribution
• Well-drained, upland and riparian forests;
• Sea level to tree line;
• From northern California, northwest along the
coastline to the Alaska Peninsula.
Needles
• 3/4 to 1 inch long, blue-green, four-angled
with whitish lines on all sides;
• Rigid, pointed, but not sharp to the touch;
• Usually crowded on upper side of the branch.
Cones
• 1-1/2 to 2-1/2 inches long, light brown;
• Narrowly oblong, nearly stalkless, hanging
down;
• Scales thin and flexible with smooth margins.
Bark
• Thin, scaly to smooth;
• Gray-brown, with white inner bark.
Size at maturity and life span
• 40 to 70 feet tall, 6 to 18 inches in diameter;
• Reaches 80 to 115 feet tall, 30 inches in diameter;
• Tree crown, narrow or spire-like;
• Can live an age of 250 to 300 years.
Habitat and distribution
• From sea level to tree line on a wide variety of
habitats;
• Throughout southcentral and interior Alaska
east through Canada to Atlantic Ocean, from
the northern tree line south to the Great Lakes.
White spruce – Picea glauca
Sitka Spruce – Picea sitchensis
White spruce
hybridizes with
Sitka spruce where
their ranges
overlap, forming
Lutz spruce,
Picea xlutzii.
It shows
characteristics
intermediate
between the two
parent trees.
Shore pine – Pinus contorta var. contorta
Needles
• 1/2 inch long, light blue-green, four-angled
with whitish lines on all sides;
• Blunt-pointed;
• Current year twigs with short red or brown
hairs.
Cones
• 1 inch long, rounded and dark;
• Scales rigid and brittle, margins rounded to
toothed;
• Stay on for several years, hang on short stalks.
Bark
• Thin, gray to blackish, becoming flaky with
age;
• Inner bark is yellow.
Size at maturity and life span
• 15 to 30 feet tall and 3 to 6 inches in diameter,
larger in ideal situations;
• Can reach 250 years in age.
Habitat and distribution
• Wet and cold sites on flats or north-facing
slopes, also in bogs;
• Usually at lower elevations;
• Throughout southcentral and interior Alaska
east through Canada to Alaska Ocean, from the
northern tree line south to the Great Lakes.
Needles
• 1 to 2-1/4 inches long;
• Two half-round needles in a bundle together
making a cylinder when pressed together.
Cones
• Light brown, egg-shaped, 1-1/4 to 2 inches
long;
• Woody, stiff prickles at the tip of each cone
scale;
• Pointed backwards on branches.
Bark
• Dark brown to blackish;
• Resinous and scaly, becoming furrowed with
age.
Size at maturity and life span
• Shrub-sized and contorted in bogs;
• Often a scrubby tree, 20 to 40 feet tall and 8 to
12 inches in diameter;
• To 75 feet tall and 18 to 32 inches in diameter
on well-drained, sunny sites;
• Lives 200 to 600 years.
Habitat and distribution
• Abundant in and adjacent to bogs;
• Sea level to subalpine;
• From northern California to Yakutat, Alaska.
© Mary Stensvold
Shore pine – Pinus contorta var. contorta
Black spruce – Picea mariana
Black spruce – Picea mariana
Tamarack – Larix laricina
Needles
• Deciduous, soft, flexible, 1 inch long;
• In clusters of 10 to 20 on short spur branches;
• Blue-green needles turn golden yellow and are
shed in the fall.
Cones
• 1/2 inch long, dark brown;
• With about 20 rounded, finely toothed scales;
• Held upright on short stalks from horizontal
twigs.
Bark
• Young trees with dark gray, smooth, thin;
• With age becomes reddish brown, scaly, exposing darker inner layer.
Size at maturity and life span
• 30 to 60 feet tall, 4 to 16 inches in diameter;
• 100 to 200 years.
Habitat and distribution
• Bogs, moist places, and along river drainages;
• From the northern slopes of the Alaska Range
to the southern slopes of the Brooks Range,
east across Canada to Atlantic Ocean, from the
northern tree line south to the Great Lakes.
Paper birch – Betula neoalaskana (formerly B. papyrifera var. humilis)
Leaves
• 1-1/2 to 3 inches long, 1 to 2 inches wide;
• Broadly oval with long-pointed tip;
• Margins coarsely double-toothed;
• Yellow-green, paler yellowish-green underneath;
• Twigs with dense covering of resin dots.
Fruit
• Nutlets borne in short, greenish-brown, dry, 1
to 1-1/4 inch-long catkins;
• Nutlets tiny, with wings broader than the body.
Bark
• Red-brown on young trunks;
• Lightens with age;
• Smooth, thin, paper-like and peeling.
Size at maturity
• To 80 feet tall, 4 to 24 inches in diameter.
Habitat and distribution
• Common in a variety of habitats, often in
mixed forests with black and white spruce;
• From interior Alaska across northern North
America to the southwest side of Hudson Bay.
Paper birch – Betula neoalaskana
Tamarack – Larix laricina
Kenai birch
(Betula
kenaica) is
nearly identical
to paper birch
except for
slightly smaller
size, leaves,
and fewer
resin dots on
twigs. This tree
is endemic to
Alaska.
Balsam poplar – Populus balsamifera
subsp. balsamifera
Black cottonwood
(Poplus balsamifera
subsp. trichocarpa)
is nearly identical to
balsam poplar except
leaves are whitish
underneath
and it grows
in southcoastal Alaska.
Hybridizes with
balsam poplar
where ranges
overlap. This
is the largest
broadleaf tree in
Alaska.
Leaves
• 1 to 31/2 inches long;
• Nearly round, pointed at tip and rounded at
base, edged with many small rounded teeth;
• Shiny green, pale underneath;
• Leaf stalks flat, allowing leaves to tremble in
the slightest breeze.
Fruit
• Capsules on 3 to 4 inch-long catkins;
• Capsules contain numerous tiny cottony seeds.
Bark
• Smooth, greenish white;
• Important wildlife food.
Size at maturity and life span
• 20 to 40 feet tall, 3 to 12 inches in diameter;
• 80 to 100 years average, 200 years maximum.
Habitat and distribution
• South-facing slopes and well drained benches;
• Propagates from root sprouting after disturbance;
• Throughout interior and southcentral Alaska,
across Canada and south to New Mexico;
• Widest distribution of any native tree in North
America.
Quaking Aspen – Populus tremuloides
Balsam poplar – Populus balsamifera subsp. balsamifera
Leaves
• 3 to 6 inches long, 2 to 4 inches wide;
• Broad at base, narrowing to a point at the tip;
• Dark shiny green above, rust-colored underneath;
• Swelling leaf buds are sweetly aromatic in the
spring.
• Fruit
• 2-parted capsules on 6 inch-long catkins contain numerous tiny cottony seeds.
Bark
• Young stems greenish to reddish brown;
• With age becomes thick and deeply furrowed.
Size at maturity and life span
• 80 to 100 feet tall, to 3 feet in diameter;
• 100 to 200 years.
Habitat and distribution
• River valleys and flood plains, alluvial fans,
glacial outwash areas, lake shores;
• A shade-intolerant pioneer species;
• From interior Alaska across northern portions
of North America.
Quaking Aspen – Populus tremuloides
Scouler willow – Salix scouleriana
Leaves
• 2-6 inches long;
• Elliptic to ovate, shallowly lobed with coarse,
rounded teeth;
• Leaf margins rolled under;
• Dark green, minute rust-colored hairs underneath.
Fruit
• Look like tiny pine-cones;
• Seeds, tiny dry nutlets with two narrow wings.
Bark
• Thin, smooth, grayish;
• Often appearing white due to incrustation by
pale, flat lichens.
Size at maturity and life span
• 20 to 80 feet tall, 4 to 25 inches in diameter;
• 60 to 90 years;
• Rapid growth when young, but short lived.
Habitat and distribution
• Along rivers, floodplains, open gravelly areas,
disturbed areas to 1,000 feet in elevation;
• Often quickly colonizes disturbed areas;
• Most common hardwood on the Pacific coastline;
• From mid-California to Yakutat, Alaska.
Leaves
• 2 to 5 inches long, and 1/2 to 1-1/2 inches
wide;
• Wider above middle, short-pointed at tip,
edges without teeth;
• Young leaves velvety hairy;
• Older leaves dark green, sparse white to rusty
hair underneath;
• Crowded at ends of twigs.
Fruit
• Seed capsules long, slender, gray-wooly.
• Bark
• Smooth gray, becoming dark brown, divided
into broad flat ridges.
Size at maturity
• Usually about 15 feet tall, 4 inches in diameter;
• Can grow to be 50 to 60 feet tall, 16 to 20
inches in diameter.
Habitat and distribution
• Colonizes burned-over areas, thrives away
from water;
• Forms thickets, often found along forest edges;
• A fast-growing, short-lived pioneer;
• From interior Alaska east to Saskatchewan and
south to New Mexico.
Scouler willow – Salix scouleriana
Red alder – Alnus rubra
Red alder – Alnus rubra
A
laska spans a vast array of ecosystems
from open, wind-swept tundra bordering
the Artic Ocean, and Bering Sea through
expansive boreal forests of the Interior to
impressive temperate rain forests along the Pacific
Coast.
Tree composition changes with the prevailing
climate across the state. In the Interior, principal
species include white spruce, birch, and quaking
aspen on uplands, black spruce and tamarack
in forested wetlands, and balsam poplar within
floodplains. Willows are abundant in the Interior
as well, however most do not reach tree size.
The coastal temperate rain forests of southcentral
and southeastern Alaska are comprised mainly
of western hemlock, and Sitka spruce. Mountain
hemlock, Alaska yellow-cedar, western redcedar,
and shore pine are most often encountered where
soils are more poorly drained. Deciduous trees
are uncommon in the temperate rain forests of
Alaska, and are represented mainly by red
alder and black cottonwood.
This brochure was produced by the
Alaska Region Ecology and Botany
Programs.
Copyright illustration by Bruce
Lyndon Cunningham, Forester/
Artist, Nacogdoches, Texas are used
with his permission and funded by
the Alaska Region Natural Resources
Conservation Education Program.
Illustrations are not to scale.
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The Alaska Region of the USDA Forest
Service is an equal opportunity provider
and employer. To file a complaint of
discrimination, call (202) 720-5964.