Trees of Alaska

Large trees without flowers or fruit, includes pines, larches, spruces, hemlocks, firs, and Douglas-firs. Resinous trees that are mostly evergreen with a straight axis and narrow crown, usually with soft, light weight wood.

Leaves: The leaves are mostly alternate or whorled, sometimes of 2 forms, narrow and needlelike.

Cones: The pollen and seeds borne on same plant in separate cones. Male cones are small and herbaceous; female cones are large and woody, composed of spirally arranged flattened cone-scales. Usually 2 naked seeds at base of cone-scale, mostly with wing at end.

Black Spruce, Picea mariana

Description: A tree with open, irregular, conical crown, with short horizontal or dropping branches. A shrub at tree line.

Height: 20’-60’ (6-18m)

Diameter: 4-12” (0.1 – 0.3m)

Needles: Are evergreen, ¼ - 5/8’ (6-15 mm) long. The needles are stiff, 4-angled, and sharply pointed. They spread from all side of the twig from very short leafstalks. They are ashy blue-green with whitish lines.

Bark: Color ranges from gray to blackish. It is thin and scaly and the cut inner surface is yellowish.

Twigs: They are brown, slender, hairy, and rough with peg-like bases.

Cones: 5/8 – 1 ¼” (1.5 – 3cm) long, and are egg-shaped or rounded. Their coloration is dull gray. Cones are often located in clusters near the top of the crown. The cone-scales are stiff and brittle, rounded and finely toothed. The seeds are paired, brown, with long-winged seeds.

Habitat: Black spruce are found in wet soils and bogs. They a re found in peats, clays, and loamy soils. Often in pure stands.

Range in Alaska: Found throughout most of the state.

The small size of black spruce limits lumber production. The lowest branches take root by layering when deep snows bend them to the ground, forming a ring of small trees around a large one. These trees are often easily distinguished from white spruce by their thin, scraggly appearance and the black hairs found on the twigs. Black spruce is one of the most important trees to the Dena’ina Indians. Their word for spruce, “Ch’vala” is also the name for tree. All three species of spruce are called by this name, however, they differentiate growth forms (which often differentiates species) by various names. Refer to Tanaina Plantlore for more information about native uses of these trees.

White Spruce, Picea glauca

Description: An evergreen tree with rows of horizontal branches forming a conical crown. It can also be found stunted and/or as a shrub at tree line.

Height: 40 – 100’ (12 – 30m)

Diameter: 1 – 2’ (0.3 – 0.6m)

Needles: They are evergreen and are ½ - ¾” (12 – 19mm) long; stiff, 4-angled and sharply pointed. The needles are spread mainly from the upper side of twigs with very short leafstalks. Their color is blue-green with whitish lines and they exude a skunk-like odor when crushed.

Bark: Ranges in color from gray to brown and is thin. The texture can be smooth or scaly. The cut surface of the inner bark is whitish.

Twigs: They are orange-brown, slender, and hairless. The twigs have a rough texture with peglike bases.

Cones: Range in size from 1 ½ - 2 ½” (4 – 6cm). The cones have cylindrical shape, are shiny light brown, and hang the end of twigs until they fall at maturity. The scales are thin and flexible with neatly straight margins and without teeth. The brown seeds are in pairs and have long wings.

Habitat: White Spruce can be found in a wide variety of soil types; they sometimes occur in pure stands.

Range in Alaska: These trees occur throughout much of the state, but they are absent from the fare north, west, and the Alaska Peninsula.

This is one of the most common and commercially valuable trees in Alaska. It is a very important tree that supports a variety of wildlife. The tallest White Spruce are generally found along rivers, where running water thaws the soil. These trees are seldom found where permafrost is close to the surface. On average, White Spruce live to be 100 - 200 years old.

Sitka Spruce, Picea sitchensis

Description: This species is the largest of all spruce, with a tall and straight trunk from a buttressed base and a broad, open, and conical crown of horizontal branches.

Height: Up to 160’ (49m)

Diameter: 3 – 5’ (0.9 –1.5m)

Needles: Evergreen, spread from all sides of twig; 5/8” 1” (1.5 – 2.5cm) long. They are flattened and slightly keeled, sharp-pointed and dark green.

Bark: Gray, smooth, thin, and becoming dark purplish-brown with scaly plates.

Twigs: Brown, stout, hairless, and rough with peg like bases.

Cones: 2 – 3 ½’ (5 – 9cm) long. They are cylindrical, short-stalked, and light orange brown. The cones hang at the ends of twigs and open and fall at maturity. The cone-scales are long, stiff, thin, rounded, and irregularly toothed. Seeds are brown, paired, and long winged.

Habitat: Coastal forests within the fog belt (a narrow strip of high rainfall and cool climate) up to 3000’. Found in pure stands with western hemlock.

Range in Alaska: Throughout southeast Alaska, Prince William Sound, Kodiak Island, Kenai Peninsula, and up the northern edge of the range extends just north of Girdwood (see map on following page).

This is the primary timber tree in Alaska because of its size and for the fact that it produces high-grade lumber for many uses. Was used in airplanes (including “The Spruce Goose”) and is used in musical instruments such as guitars. Sitka Spruce makes up more than 20 percent of the hemlock-spruce coastal forests of Alaska. The largest old growth trees in southeast Alaska have trunk diameters exceeding 8 feet and are 500 – 700 years old! As you make the drive form Cooper Landing to Seward, look for the change from forests dominated by White Spruce and Lutz Spruce to those of Sitka Spruce.

Lutz Spruce, Picea lutzii

Description: On the Kenai Peninsula, there are natural hybrids between White Spruce and Sitka Spruce, which are called Lutz Spruce. These hybrid trees can be recognized by their leaves and cones, which are intermediate to the parent species. The Lutz Spruce is found where the ranges of White Spruce and Sitka Spruce meet and/or overlap.

Height: 55 – 70’ (17 – 21m)

Diameter: 1 – 1 ½’ (30- 45cm)

Needles: Slightly 4-angled, but less so than in White Spruce and are similar to Sitka Spruce in the whitish upper surfaces.

Cones: Intermediate in size or as small as White Spruce. Cone-scales are short as in White Spruce, but like Sitka Spruce in being thin, light brown, and irregularly toothed.

Western Hemlock, Tsuga heterophylla

Description: This is the largest of the hemlock species. It has a long, slender, and often fluted trunk. The crown is narrow, conical, and made up of short, slender, horizontal or slightly drooping branches. The tip of the tree, or the leader, is slender, curved and drooping.

Height: 100 – 150’ (30 – 46m)

Diameter: 3 – 4’ (0.9 – 1.2m)

Needles: They are evergreen, and spread in two rows from twigs, ¼ - ¾’ (6 – 19mm) long. They are flat, flexible, rounded at the tip and very short stalked. Their coloration is dark green above, with 2 broad, whitish bands and indistinct green edges. The needles often have tiny teeth beneath.

Bark: It is reddish-brown to gray-brown, thick, deeply furrowed into broad, scaly ridges. The cut surface of inner bark is red.

Twigs: Very slender, yellow-brown, finely hairy, and rough with peglike bases.

Cones: ¾ - 1’ (2 – 2.5cm) long. They are elliptical in shape, brown, and stalkless. There are many rounded, elliptical cone-scales that hang down from the ends of twigs. The seeds are paired, long winged seeds.

Habitat: Found in moist, acidic soils, especially in flats and lower slopes, and in dense pure stands with Sitka Spruce and other conifers.

Range in Alaska: From south-central to southeastern Alaska, up to 2000 feet.

Native Americans in southeast Alaska used to make coarse bread from the inner bark of this tree. This tree is considered an important timber species for the production of alpha cellulose for making cellophane, rayon, yarns, and plastics. Western Hemlock is one of the most abundant and important tree species in southeast Alaska and forms more than 70 percent of the dense hemlock-spruce coastal forest. It is very tolerant of shade, whereas Sitka spruce needs higher levels of light.

Mountain Hemlock, Tsuga mertensiana

Description: A tree with a tapering trunk, conical crown f slender horizontal or drooping branches, and a very slender, curved, and drooping leader. This species can be found as a prostrate shrub at treeline.

Height: 30 – 100’n (9 – 30m)

Diameter: 1 – 3’ (0.3 – 0.9m)

Needles: Evergreen and usually crowded at ends of short side twigs, spreading on all sides and curving upward. They are ¼ - 1” (0.6 – 2.5 cm) long. The needles are short-stalked, flattened above, half-round, stout, blunt, and are colored blue-green with whitish lines on both sides.

Bark: Gray to dark brown, thick, and deeply furrowed in scaly ridges.

Twigs: Their coloration is light reddish-brown, mostly short and slender, finely hairy, and rough with peglike bases.

Cones: 1 – 3” (2.5 – 7.5cm) long. They are purplish turning to brown and cylindrical in shape. The cones are stalkless, hang down, and have many rounded scale-cones with paired, long-winged seeds.

Habitat: Mountain Hemlock is found in moist, coarse, or rocky soils. It can be found anywhere from sheltered valleys to exposed ridges.

Range in Alaska: South-central Alaska, from the Kenai Peninsula to southeastern Alaska.

This is a characteristic species of high mountains. In Alaska, they can be found up to 3,000 – 3,500’ in elevation. They vary greatly in size from a large tree at lower altitudes to a dwarf shrub at treeline. Hemlock trees provide shelter and food for wildlife, and generally are considered unimportant for commercial uses.

Birch Family – Betulaceae

This family includes trees that are often large (birches), and some shrubs, including alders. There are 135 species worldwide that belong to this family.

Leaves: The leaves are deciduous, alternate, often spreading in two rows, and are simple. The leaves are mostly ovate or elliptical, doubly saw-toothed with several nearly straight side veins. The paired stipules shed early.

Bark: Mostly smooth.

Flowers: The male and female flowers are on the same plant and usually appear early in spring before or with the leaves. They are tiny, greenish, with 0 – 4 sepals and no petals. Male flowers occur in long, narrow catkins, with 1 – 20 stamens. Female flowers occur in short cone-like or head-like cluster with one pistil.

Fruit: Typically occur in large numbers in a cone-like cluster, small nuts or nutlets, and the seeds are often short-winged.

Sitka Alder, Alnus sinuate

Description: A shrub forming thickets or found as a small tree, often with several trunks. The leaves are shiny yellow-green that are gummy when young.

Height: 30’ (9m)

Diameter: 8’ (20cm)

Leaves: 2 ½ - 5” (6 – 13cm) long and 1 ½ - 3” (4 – 7.5cm) wide. The leaves are ovate, shallowly wavy-lobed and doubly saw-toothed with long-pointed teeth and 6 to 10 nearly straight parallel veins on each side. They are gummy or sticky when young. They are usually shiny, speckled yellow-green on both sides, but paler and often slightly hairy underneath.

Bark: Smooth, gray, and thin. The inner bark is red.

Twigs: They are gummy, finely haired, and orange-brown when young. As they mature, they become light gray, slender, and zigzag.

Flowers: They are tiny, occurring in the spring with or after leaves. Male flowers are yellowish, drooping, and narrowly cylindrical in catkins. They measure 3 – 5” (7.5 – 13mm) long and 3/8” (10mm) wide. Female flowers reddish, in narrow cones 3/8” (10mm) long.

Cones: Between 3 to 6 are clustered on slender, spreading, long stalks, and are ½ - ¾” (12 – 19mm) long. They are elliptical in shape with many hard black scales, and the cones remain attached. Tiny, elliptical, flat nutlets with 2 broad wings. The cones mature in summer.

Habitat

Found along streams, lakes, and valleys.

Range in Alaska

Southwest, southcentral, and southeastern Alaska.

Sitka Alder is a pioneer species in disturbed places, such as landslides, logged areas, fires, and glacial retreat. This species is adapted to soils too barren for other trees. It actually improves soil conditions by adding organic matter and nitrogen from bacteria, which live in its root nodules (this is known as a nitrogen-fixing plant). It generally acts as a short-lived nurse tree for Sitka Spruce, and dies when it is shaded by larger trees.

American Green or Mountain Alder, Alnus tenuifolia

Description

A shrub with spreading, slender branches, or also found occasionally as a small tree. Often found in thickets.

Height: up to 30’ (9m)

Diameter: 6” (15cm)

Leaves: Occur in 3 rows, 1 ½ - 4” (4 – 10cm) long, and 1 – 2 ½” (2.5 – 6cm) wide. Their shape is ovate or elliptical, wavy-lobed, doubly saw-toothed, and rounded at base. There are 6 – 9 nearly straight parallel veins on each side. The coloration is dull green above and light yellow-green and sometimes finely hairy beneath.

Bark: Gray, smooth, and thin, but becoming reddish-gray and scaly with increased age.

Twigs: They are slender, reddish, and hairy when young. As they age, they become gray with a 3-angled pitch.

Flowers: The flowers are tiny and open in early spring before the leaves do. Male flowers are yellowish, in the form of catkins, 1 – 2 ¾” (2.5 – 7cm) long. Female brownish, in narrow cones ¼” (6mm) long.

Cones: The cones are found clustered on short stalks in groups of 3 - 9. They are 3/8 – 5/8” (10 – 15mm) long, elliptical in shape with many hard black scales. They mature in the summer and remain attached. The seeds are tiny elliptical flat nutlets.

Habitat: Mountain Alder is found on stream banks, bogs, and areas with moist soils.

Range in Alaska: From western to Southcentral Alaska.

Native Americans made a red dye from the powdered bark of the Mountain Alder. Alder twigs and buds are an important winter food source for ptarmigan. In the fall and winter, the seeds or nutlets are eaten by many songbirds.

Paper Birch, Betula papyrifera

Description: One of the most easily distinguished trees with a narrow, open crown of slightly drooping to nearly horizontal branches, and conspicuous white bark. Paper Birch is sometimes found as a shrub. In Alaska, there are 3 geographical varieties of Paper Birch in Alaska, and they hybridize with each other wherever their ranges meet.

Height: 50 – 70’ (15 – 21m)

Diameter: 1 – 2’ (0.3 – 0.6m)

Leaves: They are 2 – 4” (5 –10cm) long, 1 ½ - 2” (4 – 5cm) wide. Their shape is ovate, long-pointed, coarsely, and doubly saw-toothed. There are usually 5 – 9 veins on either side, and coloration is dull green above, light yellow-green and nearly hairless beneath, turning light yellow in autumn.

Bark: The coloration is chalky to creamy white, and it its thin, smooth, with horizontal lines. It separates into papery strips to reveal orange inner bark. The bark becomes brown, furrowed, and scaly at base, and bronze to purplish in varieties.

Twigs: Are reddish-brown, slender, and mostly hairless.

Flowers: Bloom in early spring and are tiny. Male flowers are yellowish, with 2 stamens and in many long drooping catkins near tip of twigs. Female flowers are greenish; in short, upright catkins back from the tip of the same twigs as the male flowers.

Cones: 1 ½ - 2” (4 – 5cm) long. They are narrowly cylindrical, brownish, hand on slender stalks, with 2-winged nutlets that mature in autumn.

Habitat: Found in moist upland soils and cut-over or burned lands, often found in pure stands.

Range in Alaska: Found throughout most of the state, from western through Southcentral Alaska, the Southeastern Panhandle, and north to the Arctic Circle.

Native Americans used the Paper Birch for the making of canoes and many types of containers. The bark should never be peeled from a live tree, as this leaves permanent, ugly black scars. Birch trees produce a bitter tasting chemical known as salicin (similar to aspirin), to deter moose and other animals from browsing on their branches.

Willow Family – Salicaceae

Trees in the willow family are deciduous and often aromatic trees and shrubs. There are approximately 350 species in this family worldwide, and most of them occur in north temperate and arctic regions.

Leaves: Alternate, simple, mostly toothed, with paired stipules.

Flowers: Tiny male and female flowers on separate plants, crowded in narrow catkins. Male flowers have cuplike disk or 1 – 2 glands and 1 –40 stamens separate or united at base. Female flowers have one pistil

Fruit: A capsule opening in 2 –4 parts, containing many tiny seeds with cottony hairs.

Quaking Aspen, Populus tremuloides

Description: This is the most widely distributed tree in North America. A narrow, rounded crown of thin foliage characterizes Quaking Aspen.

Height: 40 – 70’ (12 – 21m)

Diameter: 1 – 1 ½’ (0.3 – 0.5m)

Leaves: 1 ¼ - 3” (4 – 7.5cm) long. They are nearly round, abruptly sharp-pointed, and rounded at the base. They are also finely saw-toothed and thin. The coloration is shiny green above and dull green below. The leafstalks are slender and flattened (which is why they “quake” in the slightest breeze).

Bark: Whitish to yellowish, smooth and thin, but on large trees, the bark becomes dark gray, furrowed and thick.

Twigs: Are shiny brown, slender, and hairless

Flowers: Bloom in the spring before the leaves open up. They are in the form of catkins 1 – 2 ½” (2.5 – 6cm) long, brownish, and the male and female flowers occur on separate trees.

Fruit: ¼” (6mm) long, narrowly conical, and light green capsules in drooping catkins up to 4” long. They mature in late spring and split into two parts. They produce many tiny, cottony seeds, but most of the propagation occurs by root sprouts.

Habitat: Occur in many soil types, especially sandy and gravelly slopes. They are often found in pure stands.

Range in Alaska: Found throughout most of Alaska, from western through southcentral Alaska, and north to the Arctic Circle.

The name for this tree comes from the leaves, which tremble in the slightest breeze on their flattened leafstalks. This “quaking” serves to act as physical defense against insects that feed on the leaves by shaking them off the leaves. Quaking Aspen is a pioneer species that quickly invades burned areas, and it is a short-lived species that is often replaced by conifers. The twigs and foliage are browsed by moose, sheep, and goats. Beavers, rabbits, and porcupines feed on the bark and foliage. Grouse and ptarmigan feed on the buds during the winter.

Black Cottonwood, Populus trichocarpa

Description: This is the tallest cottonwood with an open crown of erect branches and sticky resinous buds with balsam odor.

Height: 60 – 120” (18 – 37m)

Diameter: 1 – 3’ (0.3 – 0.9m), but sometimes much larger.

Leaves: 3 – 6” (7.5 – 15cm) long, 2 –4” (5 –10cm) wide, larger on young twigs. Their shape is broadly ovate, short or long pointed at tip, finely wavy toothed, and rounded or slightly notched at base. They are shiny dark green above and whitish with rusty veins below, and they turn yellow in autumn.

Bark: Gray and smooth, but becoming thick and deeply furrowed into flat, scaly ridges.

Twigs: Brownish, stout, and often hairy when young.
Flowers: Bloom in early spring in the form of catkins, 1 ½ - 3 ¼” (4 – 8cm) long. The coloration is reddish-purple, and male and female flowers occur on separate trees.

Fruit: Small, ¼” (6mm) in diameter, in the shape of round capsules. They are light brown and hairy. They mature in the summer and release their “cottony” seeds.

Habitat: Black Cottonwoods are found in moist to wet soils of valleys, mostly on stream banks and flood plains. They may also be found on upland slopes.

Range in Alaska: Southeast to southcentral Alaska.

The Black Cottonwood is the tallest native western hardwood (or broadleaf tree). The wood is used for boxes, crates, and pulpwood. Black Cottonwood hybridizes with Balsam Popular in southern Alaska, just north of Anchorage. Artists and crafts-people use the bark in carvings. This tree is not easily distinguished from its close relative, the balsam poplar.

Balsam Poplar, Populus balsamifera

Description: A large tree with a narrow, open crown of upright branches and fragrant, resinous buds with a strong balsam odor.

Height: 60 – 80’ (18 – 24m)

Diameter: 1 – 3’ (0.3 – 0.9m)

Leaves: 3 – 5” (7.5 – 13cm) long, and 1 ½ - 3” (4 – 7.5cm) wide. They are ovate, pointed at tip, and rounded or slightly notched at the base, finely wavy toothed, and hairless or nearly so. The coloration is shiny dark green above and whitish (often rust colored veins) beneath. Leafstalks are slender, round, and hairy.

Bark: Light brown, smooth, but becoming gray and furrowed into flat, scaly ridges.

Twigs: Brownish and stout, with large sticky buds producing fragrant, yellowish resin.

Flowers: Catkins 2 – 3 ½” (5 – 9cm) long, that are brownish. Male and female flowers bloom on separate trees in early spring.

Fruit: 5/16” (8mm) long, egg shaped capsules that are pointed, light brown, and hairless. They mature in the spring and split into two parts, releasing many tiny cottony seeds.

Habitat: Balsam Poplars are found in moist soils of valleys, stream banks, and floodplains. Often found in pure stands.

Range in Alaska: North of Anchorage, throughout the interior, and up north to the Arctic Circle. Balsam Poplar hybridizes with Black Cottonwood where their ranges meet and/or overlap.

Balsam Poplar is the northernmost hardwood tree, as it can be found in scattered groves on the Arctic Slope. Artists and crafts-people use the bark in carvings.