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This publication was produced by theColorado State Forest Service.If you would like further assistance or other publications,please stop by or call us.Colorado State Forest ServiceColorado State UniversityFoothills Campus5060 Campus DeliveryFort Collins, CO 80523-5060Phone: (970) 491-6303FAX: (970) 491-8645Colorado NativeTree Guide
The following is a key to the identification of some of the morecommon trees in Colorado. This guide does not include alltree species which may occur in Colorado.To Identify a Tree:Select some typical leaves or needles, and if possible,some cones and bark.Read the first leaf description below.GlossaryLanceolate-narrow leaf, broadest toward the base. Lance-shaped,about 5 times as long as wide.Node-place along the stem where leaves, buds, or branch stems arise.NodeSelect the choice that best describes the leaf or needle.Ovate-egg-shaped with the broadest area toward the base.Go to the number instructed, continuing in the samemanner until a tree name is given.Pinnate-arranged with leaflets or veins arising atopposite sides of a central axis.If the tree has needle- or scale-like leaves go to 1If the tree has ordinary leaves, go to 13Obovate-reverse ovate: oval, with the broader end at the tip.1 If the leaf is a needle, go to 2If the leaf is a scale, go to 8Racemes-an unbranched flower cluster, consisting of a singlecentral stem, along which individual flowers grow on small stems.2 If the needles are surrounded by a sheathat the base, go to 32If the needles are not in bundles not surrounded by asheath at the base, go to 915
3 If needles are borne singly, go to 423 This tree is a.RIVER BIRCH (Betulaoccidentalis) Leaves are 1-2inches long, thin, and oval orobovate shaped. They are alsodark green on top and yellowgreen on bottom. Bark is a reddish-brown and is shiny. Fruit is alight brown cones, about 1 inchlong.If the needles are mostly in bundles of two, go to 5If the needles are mostly in bundles of three, go to 6If the needles are in bundles of five, go to 74 This tree is a.Or a.CHOKECHERRY (Prunusvirginiana melanocarpa) Leavesare broadly obovate, 2-4 incheslong and 1-2 inches wide. Floweris white and .5 inches in diameter,in racemes 3-6 inches long.Cherries are .3 inches in diameter.Bark smells bad and is lustrousbrown and later becomes scaly.24 This tree is a.GAMBEL OAK (Quercusgambelii) Leaves are 2-7 incheslong and 1.5-3.5 inches wide with7-11 lobes. The fruit is an acorn.14SINGLELEAF PIÑON (Pinusmonophylla) Needles are 1-1.5inches long. Cones are round andabout 2 inches long. Needles areborne singly. (Occurs rarely inSW Colorado.)5 This tree is a.PIÑON PINE (Pinus edulis)Has large edible seeds. Needlesare 1-1.5 inches long. Cones areround, resinous, and about 2inches long. The tree is fairlysmall, 20-50 feet tall, with arounded crown and short trunk.3
Or a.22 This tree is a.SANDBAR WILLOW (Salixexigua) Leaves are narrowlylanceolate leaves, 2-6 inches longand .3-.5 inches wide. Bark isreddish-brown and scaly. Fruit iscottony.LODGEPOLE PINE (Pinuscontorta) Needles are 1-3 incheslong and are stiff and dark green.Cones are closed and typicallyattached to the tree, but openwhen heated.6 This tree is a.PONDEROSA PINE (Pinusponderosa) Needles are 3-6inches long, dark yellow-green,and form tufts near the end of thebranches. Cones are 3-6 incheslong with the scales tipped by astiff prickle. Bark on mature treesis reddish orange and sometimessmells like vanilla. Bark on youngtrees is dark.7 This tree is a.LIMBER PINE (Pinus flexilis)Needles are 2-3.5 inches long,slender, and blue-green in color.Cones are columnar and 3-8inches long. Branches are fairlybendable.4Or a.PEACHLEAF WILLOW (Salixamygdaloides) Leaves arebroadly lanceolate, 2-5 incheslong and .8-1.3 inches wide. Barkof large trunks is black, ridged,and furrowed.Or a.NARROWLEAF COTTONWOOD (Populus angustifolia)Leaves are 2-3 inches long and.5-1 inches wide, with teeth on theedge and a nearly round stem.There many other species of native willows and willow hybrids inColorado. These naturally occur primarily in riparian areas.13
Or a.Or a.QUAKING ASPEN (Populustremuloides) Leaves are nearlyround, 1-3 inches in diameterwith slender, flattened stems.They are green on top andsilverish below. In the fall, theleaves turn golden-yellow. Thebark is smooth, greenish-white,and marked by black, wartypatches.BRISTLECONE PINE (Pinusaristata) Needles are 1.5 incheslong, stout, and dark green incolor with white dots of sap onthem. Cones scales are tippedwith a long, stiff, incurved prickle.8 This tree is a.ROCKY MOUNTAIN JUNIPER (Juniperus scopulorum)Has scale-like, wispy branchesthat are grayish-green in colorand may be reddish in the winter.Berries are .2 inches in diameter,are blue-gray, waxy, and juicy.Tree grow to 20-40 feet tall witha short, stout, often dividedtrunk. Bark is gray-brown toreddish-brown with scales on thesurface.21 This tree is a.HACKBERRY (Celtisoccidentalis) Leaves are ovate toovate-lanceolate and are 2.3-4inches long and 1.5-2 incheswide. Fruit is dark-red to purpleand .3 inches in diameter. Bark iswarty and gray to brown.Or a.Or a.THINLEAF ALDER (Alnustenuifolia) Leaves are 2-4 incheslong and 1.5-2.5 inches wide withtoothed edges. Tree has“minature cones.” Grows alongcreeks or other moist areas.ONE-SEED JUNIPER(Juniperus monosperma)Branches are stout with yellowgreen, glandular foliage. Berriesare a 1/4 inch, dark blue, andjuicy. Usually grows as a multistemmed shrub on very poorsites.125
Or a.19 This tree is a.UTAH JUNIPER (Juniperusosteosperma) Has scale-like,yellow-green foliage. Cones areoblong, and .2 - .3 inches long.Bark is gray and broken intoelongated scales.GREEN ASH (Fraxinuspennsylvanica) Leaves are 6-9inches long with leaflets 3-4inches long and 1-1.5 incheswide. The bottom of the leafletsare smooth to hairy. Bark is thin,brown-tinged with red, andfurrowed with ridges.20 This tree is a.9 If the needles are four-sided, sharp on the endand grow from woody, peglike bases, go to 10If the needles are two-sided, rounded on the end and growdirectly from the branch, go to 1110 This tree is a.ENGELMANN SPRUCE(Picea engelmannii) Needles areplump to 4-sided in crosssections and sharp. Twigs areminutely hairy. Cones are cigarshaped, 1-2.5 inches long, lightchestnut in color. Scales arepapery thin and ragged along theouter edge. Tree grows to be100-125 feet tall. Bark ofmature tree is “flaky.”6FREMONT COTTONWOOD(Populus fremontii) Leaves aretriangular, 2-2.5 inches long and2.5- 3 inches wide. Seeds arecapsules that are usually 3, sometimes 4 valved. Bark in youngtrees is thin, smooth, and graybrown. Bark on mature trees isthick, deeply-furrowed, and darkreddish brown.Or a.PLAINS COTTONWOOD(Populus deltoides var.occidentalis) Leaves are triangular, 3-6 inches long and 4-5 incheswide. Seeds are capsules with 34 valves and are about .3 incheslong. Bark of young trees issmooth and greenish-yellow.Bark on mature trees is dark grayand furrowed.11
Or a.If seeds and/or flowers arewhite.COLORADO BLUE SPRUCE(Picea pungens) Needles are 11.5 inches long, diamond-shapedin cross sections, stiff, and verysharp. Cones are similar toEngelmann spruce but 3.5 incheslong. Tree grows to be 80-100feet tall. Bark of mature tree isgray and furrowed.REDTWIG (OR OSIER)DOGWOOD (Cornusstolonifera) The leave are roughon the top and fuzzy on thebottom. They are also large andoval. Flowers and fruit arewhite. The twigs and branchesare reddish.11 If the cones hang down, thistree is a.If the fruit is twin, blackberries.TWINBERRY HONEYSUCKLE (Lonicera involucrata)Leaves are large, opposite, and 24 inches long. Fruit is twinblackberries about 1/4 inch indiameter. Stems are gray.18 This tree is a.BOXELDER (Acer negundo)Leaves are pinnately compound.They are 6-15 inches long with3-7 coarsely toothed or shallowlylobed leaflets. Seeds are wingedand 1.5-2 inches long. Bark onyoung trees is gray-brown andslightly ridged. Bark on maturetrees is heavily furrowed.10DOUGLAS-FIR (Pseudotsugamenziesii) Needles are 1-1.5inches long. Cones hang downand are 3-4 inches long. Theyhave 3-pointed bracts stickingout from the scales. Bark ofyoung trees is gray and smoothwith resin blisters. Needle basesconsist of little stalks or “pegs.”If the leaf scars resemble “suction cups,” theneedles are soft with rounded tips, and the conessits upright on the branch falling apart at maturity,falls apart on the tree, go to 127
12 This tree is a.WHITE FIR (Abies concolor)Needles are flat, 1.5-3 incheslong, blue-green or silvery, andtend to point up. The cones areoblong, olive-green to purple, and3-5 inches long.Or a.15 If the seeds look like thisgo to 18If the seeds look like thisgo to 1916 If the leaves are triangle-shaped, go to 20SUBALPINE FIR (Abieslasiocarpa) Needles are flat, 1-1.8inches long, dark blue-green, withsilvery lines of stomata on bothsurfaces. Cones are 2-4 incheslong, purple, and cylindrical.(Corkbark fir is a subspecies ofsubalpine fir also occurring inColorado).If the leaves are ovate, ovate-lanceolate,or ovate-oblong, go to 21If the leaves are lanceolate, go to 22If the leaves are obovate, go to 23If the leaves are broad and lobed, go to 2413 If the leaves are simple, go to 14If the leaves are compound, go to 1514 If the leaves on the branch are alternate, go to 16If the leaves on the branch are opposite, go to 17817 If the seeds have wings.ROCKY MOUNTAIN MAPLE(Acer glabrum) Leaves are 3-5inches in diameter with 3-5 lobes.Wings of the seeds only spreadslightly, are .75-1 inch long andabout .3- .5 inch wide and slightlyrose colored.9
Colorado State Forest Service. If you would like further assistance or other publications, please stop by or call us. Colorado State Forest Service Colorado State University Foothills Campus 5060 Campus Delivery Fort Collins, CO 80523-5060 Phone: (970) 491-6303 FAX: (970) 491-8645 Colorado Native
