Colorado’s major tree species include bristlecone pine, Colorado blue spruce, Douglas-fir, Engelmann spruce, limber pine, lodgepole pine, narrowleaf cottonwood, quaking aspen, piñon pine, plains cottonwood, ponderosa pine, Rocky Mountain juniper, subalpine fir and white fir.
Bark: Light gray and smooth when young; red-brown with irregular, scaly ridges when mature.
Leaves: Evergreen needles are dark with white lines, they have white pitch dots on both surfaces; to 1-inch long; crowded in a long, dense mass along the twig; generally 5 in a bundle.
Fruit: Cylindrical, dark purple-brown cones; 2 to 3 inches long; 4-sided cone scales with stiff curved points; brown seeds with black mottling and detachable wing.
Elevation: 9,200 to 11,800 feet
Height: 15 to 30 feet
Habitat: On exposed, cold, dry, rocky slopes and high mountain ridges up to timberline; in pure stands or with limber pine.
Relation to Fire: Fires virtually nonexistent in these areas due to low temperatures and a short growing season.
Bark: Gray-brown with thick scales on mature trees.
Leaves: Evergreen needles are blue or light green with white lines; 1 to 1-1/4 inches long with thin, long, flexible and irregularly toothed scales; contains paired, long-winged seeds.
Fruit: Shiny light brown, cylindrical cones; 2 to 4 inches long with thin, long, flexible and irregularly toothed scales; contains paired, long-winged seeds.
Elevation: 6,700 to 11,500 feet.
Height: 70 to 115 feet.
Habitat: Well-drained, sandy soils; moist sites of narrow bottomlands or along mountains streams; often in pure stands.
Relation to Fire: Easily killed by fire due to thin bark, shallow roots and low branches.
Bark: Gray and smooth with resin blisters on young trees; red-brown, very thick and deeply furrowed with broad, often corky ridges at maturity.
Leaves: Evergreen needles are to 1-inch long with bracts at the base.
Fruit: Light brown, short-stalked cones that hang down from the branches; 1-1/3 to 3 inches long; many thin, rounded cone scales on top of long, 3-pointed, winged seeds that stick out beyond scales.
Elevation: 6,000 to 9,500 feet.
Height: 100 to 130 feet.
Habitat: Rocky soils of moist northern slopes; in pure stands and mixed conifer forests.
Relation to Fire: Thin, resinous bark of young trees makes them highly susceptible to fire; after 40 years, trees have developed a very thick layer of bark to protect them during hot ground and surface fires.
Bark: Gray-brown, thick, with flaky scales.
Leaves: Evergreen needles are deep blue-green with white lines; 5/8 to 1 inch long; slender, sharp and flexible; skunk-like odor when crushed.
Fruit: Light chestnut-colored, oblong cones; 1 to 2 inches long; in upper part of crown with scales that are paper-thin and ragged along the outer edge. Seeds have a single, long and well-developed wing.
Elevation: 8,000 to 11,000 feet.
Height: 45 to 130 feet.
Habitat: High, cold forest environments on moist, northern slopes; with subalpine fir and other conifers.
Relation to Fire: Generally killed by fire due to thin bark, shallow roots, low growing branches, tendency to grow in dense stands and support heavy lichen growth. Large trees may survive low-intensity fires.
Bark: Light gray, thin and smooth on young trees; at maturity, dark brown, thick and furrowed into scaly ridges. Young branches are very flexible, hence the name.
Leaves: Slender evergreen needles are blue-green with white lines on all surfaces; 2 to 3 inches long, typically 5 in a bundle.
Fruit: Yellow-brown, egg-shaped cones; thick, rounded cone scales that end in a blunt point; seeds are large with a very short wing.
Elevation: 5,000 – 12,000.
Height: 40 to 50 feet.
Habitat: Nutrient-poor soils on dry, rocky slopes; ridges up to timberline and often pure stands.
Relation to Fire: Young trees can be killed by any fire; mature trees can only survive low-intensity fires, but due to the sparse fuels, late snow-melt and short growing season, this species is rarely affected.
Bark: Light brown, thin with many small scales.
Leaves: Evergreen needles are yellow to dark green; 1 to 3 inches long; sharply pointed, stiff, stout, slightly flattened and often twisted; 2 needles per bundle.
Fruit: Shiny, yellow-brown, egg-shaped, serotinous* cones; to 2 inches long with raised, rounded cone scales and a tiny point. *Seeds released from cones by exposure to extreme heat.
Elevation: 6,000 to 11,000 feet.
Height: 20 to 80 feet.
Habitat: Mostly well-drained soils in high elevations, often in pure stands.
Relation to Fire: Ground fires kill many trees due to thin bark. New stands quickly establish when cones open and seeds are released.
Bark: Yellow-green and smooth on young trees; thick, gray-brown and furrowed with interlacing ridges at maturity.
Leaves: Broad-leaf foliage is shiny green with a pale underside; narrow and 2 to 3 inches long; lance shaped with a fine, serrated edge and a pointed tip.
Fruit: Light brown, hairless fruit; inch long; many broad, egg-shaped capsules that mature in the spring, then split into two parts containing many cotton-like seeds.
Elevation: 5,000 to 8,000 feet.
Height: Up to 60 feet.
Habitat: Moist soils along streams; can often be found with willows and alders in coniferous forests.
Relation to Fire: Severe fires can easily kill both young and mature trees. Young trees are able to sprout from roots and/or branches after a fire.
Bark: Green-white, smooth and thin with raised dark patches; on very large trees, trunk base is often gray, thick and furrowed.
Leaves: Broad-leaf foliage is bright green above and dull green below; rounded with a pointed tip, 1 to 3 inches wide on a flattened leaf head; nearly round and sawtoothed.
Fruit: Fruit are catkins; up to 4 inches long; many light green capsules contain 6 to 8 tiny, cotton-like seeds.
Elevation: 6,500 to 11,500 feet.
Height: 35 to 50 feet.
Habitat: Many soil types, especially on well-drained, sandy and gravelly slopes; often in pure stands.
Relation to Fire: Easily killed by fire, but quick to send out many sucker shoots; readily colonizes after a fire.
Bark: Gray, smooth and thin when young; red-brown, rough and furrowed into scaly ridges at maturity.
Leaves: Evergreen needles are stout and light green; 1 to 1-1/2 inches long; 2 in a bundle.
Fruit: Cones are yellow-brown, unique, short and squatty; 1 to 2 inches long. Each cone contains 10 to 20 large, edible, oily seeds.
Elevation: 5,200 to 9,000 feet.
Height: 20 to 50 feet.
Habitat: Open woodlands; alone or with junipers on dry rocky foothills, mesas and plateaus.
Relation to Fire: Easily killed by fire due to thin bark, relatively flammable foliage and accumulation of dead lower branches.
Bark: Green-yellow and smooth while young; dark gray, thick, rough and deeply furrowed at maturity.
Leaves: Broad-leafed foliage is glossy and yellow-green; 3 to 6 inches long, 4 to 6 inches wide; toothed margins.
Fruit: Inch long with capsules containing 3 to 4 valves; many tiny, cotton-like seeds inside valves.
Elevation: 3,500 to 6,500 feet.
Height: 36 to 190 feet.
Habitat: Found in floodplains, bordering streams, near springs and in moist woodlands; pure stands or with willows.
Relation to Fire: Generally killed by fire; very poor sprouting response.
Bark: Dark on young trees; nearly 3 inches thick, red-orange and furrowed into large, flat scaly plates on mature trees.
Leaves: Evergreen needles are stiff, dark yellow-green; 3 to 7 inches long; typically in bundles of 3 that form tufts near the ends of branches.
Fruit: Light red-brown cones; 3 to 4 inches long; egg-shaped with scales that are tipped by a sharp point; small, long-winged seeds.
Elevation: 6,300 to 9,500 feet.
Height: 40 to 160 feet.
Habitat: Dry, nutrient poor soils in open park-like stands or with Douglas-fir, Rocky Mountain juniper and spruce.
Relation to Fire: Resistant to fire, due to open crowns, thick, insulating bark, self-pruning branches, high moisture content in the leaves and thick bud scales.
Rocky Mountain Juniper
Bark: Gray-brown, thin, fibrous; shreds with a red-brown color underneath.
Leaves: Evergreen scalelike needles are small, gray-green or silvery.
Fruit: Blue-gray berries; waxy and juicy; inch in diameter; typically two-seeded.
Elevation: 5,000 to 9,000 feet.
Height: 20 to 50 feet.
Habitat: Grows on rocky soils in the foothills and on the plains; often associated with piñon pines.
Relation to Fire: The resinous wood is very flammable. Low intensity fires easily kill this tree due to its thin bark and compact crown.
Bark: Gray and smooth with resin blisters while young; shallow fissures and scaly when mature.
Leaves: Evergreen needles are dark, blue-green with silvery lines on both surfaces; 1 to 1-1/2 inches long; flat and blunt tipped; crowded and curved upward on twigs at nearly right angles.
Fruit: Upright, cylindrical, very dark purple, 2 to 4 inches long in the upper part of the crown; fine, hairy, cone scales; long, broad-winged seeds. These deciduous cones fall apart when mature so they are rarely found on the ground.
Elevation: 8,000 to 12,000 feet.
Height: 60 to 100 feet.
Habitat: Cold, high elevation forests; with Engelmann spruce and other conifers.
Relation to Fire: Generally killed by low-intensity fires because of thin, flammable bark, shallow roots, low-growing branches and dense growing conditions. Seeds readily germinate on recently burned ground.
Bark: Light gray and smooth with resin blisters on young trees; deeply furrowed into corky ridges and orange cracks when mature.
Leaves: Evergreen needles are light blue-green or silvery with white lines on both surfaces; 1 to 3 inches long; flat and rounded.
Fruit: Oblong, olive-green to blue cones; 3 to 5 inches long; upright on topmost twigs; fine, hairy cone scales; paired, long-winged seeds.
Elevation: 7,900 to 10,200 feet.
Height: 60 to 125 feet.
Habitat: Moist soils of high mountain valleys; in pure stands and with other firs.
Relation to Fire: Young are usually killed by low-intensity fires due to thin, resin blistered bark and drooping lower branches; mature trees are moderately fire tolerant.