San Juan National Forest

TREES OF THE SAN JUAN NATIONAL FOREST

Conifers

PINES.—Five species. The pines have their needles gathered together at the base in bundles of from two to five. The cones are woody and pendent.

LIMBER PINE (Pinus flexilis).—Needles are fine, almost silky, dark green, 1-1/2 to 3 inches long, always in bundles of five. Cones are 3 to 5 inches long, with seeds about 13 inch long; scales smooth; bark light gray or silvery white except on old trunks which are blackish brown and furrowed.

BRISTLECONE PINE (Pinus aristata).—Needles grow five in a bundle, about 1 to 1-1/2 inches long, almost always covered with tiny specks of pitch. Cones have long, slender, sharp bristles on the tips of the scales, which give the tree its name.

PONDEROSA PINE (Pinus ponderosa).—This tree was formerly known as western yellow pine. Needles are 3 to 7 inches long, deep green, usually three in a cluster but often only two, in tufts at the ends of the branches. Cones are 3 to 6 inches long, oval shaped; scales are armed with spines. When young the bark is dark and the tree is often called "black jack," or "bull" pine. When older the bark is yellowish and occurs in thick, scaly ridges.

PINON OR PINON PINE (Pinus edulis).—Pinon is a short scrubby tree, often growing in mixture with juniper, and is confined to the foothills. Needles grow in bundles of two, rarely three, 7/8 to 1-3/4 inches long. Cones are 1-1/2 to 2 inches long and almost as broad and contain large seeds which are the pinon nuts of trade.

LODGEPOLE PINE (Pinus contorta).—This tree is not native to this locality, but is being planted with success on the Lime Creek burn. A few young trees may be found growing along the Durango-Silverton highway on Lime Creek, as the result of some experimental seed broadcasting in the summer of 1911. Needles are yellow-green, 2 or 3 inches long, and grow in bundles of two. Bark is thin; cones are one-sided, 1-1/2 to 2 inches long, and cling to the branches for years without opening or dropping their seeds. Cone scales are armed with short spines.

SPRUCES.—Two species. Needles are scattered over the twigs singly; sharp-pointed, four-sided, leaving twigs rough like a grater when they fall off. Cones are pendent, with parchment-like scales, falling off the tree whole.

ENGELMANN SPRUCE (Picea engelmannii).—The new-growth twigs are covered with soft, short hair. Needles are less rigid and less sharply pointed than those of spruce, green, dark blue, or pale steel blue. Cones are 1 to 2 inches long; bark is dark reddish brown and separates in the form of small rounded scales. The main trunk, in contrast to blue spruce, is smooth and clean.

BLUE SPRUCE (Picea pungens).—The new-growth twigs are always smooth. Needles are stiff, with sharp points, varying in color from silvery blue to green. Cones are from 2-1/2 to 5 inches long, averaging twice the length of Engelmann spruce cones. Bark of mature trunks is gray and deeply furrowed. The main trunk always has numerous short twigs pushing out between branches.

FIRS.—Three species. Needles are blunt, flat, and soft to the touch, without any stem where they join the branches. They leave flat, round scars when they fall off, in contrast to short stubs left on twigs by spruce needles. Cones, unlike those of other species, stand erect. In the fall, the cones fall to pieces and leave only spikes on the branch. Buds are blunt and pitchy. Blisters containing liquid pitch or balsam are scattered over the smooth bark.

ALPINE FIR (Abies lasiocarpa).—Needles are flat, about 1 to 1-3/4 inches long, without any stem where they join the branches. Cones are 2-1/4 to 4 inches long, dark purple; bark is smooth and grayish white except on older parts of the trunk, where it is broken into ridges. Tree has a sharp, spirelike crown. Grows at high altitudes, usually with Engelmann spruce.

CORKBARK FIR (Abies arizonica).—The trunk, crown, cones, and leaves of the corkbark and alpine fir are so alike in general appearance that the two cannot be readily distinguished by these features. The cone scales of the corkbark fir are of a different form than those of the alpine and the bracts borne on the backs of the scales also differ materially in form. The ashy-gray, soft, corky trunk-bark of corkbark fir alone readily distinguishes this tree from alpine fir.

WHITE FIR (Abies concolor).—Needles are longer and coarser than those of alpine fir, often 2 inches or more long. Cones are usually dark purple, sometimes grayish green. Bark becomes quite thick on old trunks near the ground, deeply divided into broad, rounded ridges broken on the surface into irregular shaped plate-like scales. Grows only at lower altitudes, often with ponderosa pine and Douglas fir.

DOUGLAS FIR (Pseudotsuga taxifolia).—Though similar in name, this species has no direct relationship to the true fir. Needles are flat, 3/4 to 1-1/2 inches long, with short stems that join them in the branches. Cones are pendent, with three-pronged bracts protruding between the cone scales. They are persistent and fall off the tree whole. Buds are smooth, red brown, shiny, and sharp-pointed.

JUNIPERS.—Three species—two small trees and a shrub. The fruit is berrylike, bluish in color. The needles are merely small green scales attached closely to the twigs, though sometimes spreading, and about 1/2 inch long, making the twigs very prickly to the touch.

ROCKY MOUNTAIN JUNIPER (Juniperus scopulorum).—Berries are about the size of small peas, bluish or black, usually with two seeds, maturing in 2 years. The bark is scaly, the twigs slender and graceful. The heartwood is red.

ONE-SEED JUNIPER (Juniperus monosperma).—The berries are small, mostly less than 1/4 inch in diameter and usually contain only one seed. They are covered with a bluish bloom which may be rubbed off, exposing the true reddish or coppery color. They mature in 1 year. The twigs are stiff and stout. The heartwood is brown.

DWARF JUNIPER (Juniperus communis).—Always a shrub, 1 to 3 feet high; leaves in groups of three, separate on the branches, sharp-pointed. Branches not stiff.

Broadleaf Trees

ASPEN (Populus tremuloides).—Flat, nearly heart-shaped leaves about 2 inches across, that quiver characteristically in a breeze; bark is whitish or very pale green, smooth, with black scars where branches have dropped off. Trees rarely more than 60 feet high.

NARROWLEAF COTTONWOOD (Populus augustifolia).—Usually a tall tree, 40 to 60 feet in height. Bark is dark gray, heavily ridged half or two-thirds of the way up the tree, above that, smooth, pale green. Leaves are 1/4 to 1 inch wide and 2 to 3 inches long, very similar to willow leaves. Usually found along streams at lower elevations.

THINLEAF ALDER (Alnus tenuifolia).—Found along and overhanging streams, usually in clumps, several trees growing from the same root; frequently 4 to 6 inches in diameter, and 15 to 25 feet high. The leaves are large and sharply double-toothed. The mature seed-bearing fruit is noticeable in winter.

BOXELDER (Acer negundo).—Leaves are compound, 3 to 5 on a single stalk; tree low and freely branched, 25 to 40 feet in height and up to 12 inches in diameter; has drooping clusters of greenish flowers; seed paired and winged.

ROCKY MOUNTAIN MAPLE (Acer glabrum).—Usually a shrub but may attain a height of 20 to 30 feet. Paired opposite buds, sharply lobed leaves, light gray bark, and paired, winged seed. Leaves 1 to 2 inches long, opposite each other.

WILLOWS (Salix sp.).—This is the common shrub of creek bottoms. Its leaves are usually narrow and sharp-pointed. Some willows attain a diameter of 4 inches and a height of 15 to 25 feet. Buds are covered by a single scale.

WESTERN CHOKECHERRY (Prunus demissa).—Clustered flowers and fruit; alternate leaves sharply pointed. Bark, leaves, and seed bitter; fruit black. Tree, or more often a shrub, 3 to 15 feet high.

SCRUB OAK (Quercus sp.).—Usually a shrub, rarely over 15 feet high; alternate leaves, smaller at the base than at the ends, with deep lobes, frequently drying on the tree and remaining over winter. Fruit a short, pointed acorn. Forms dense thickets at lower elevations. Often valuable for fence posts.