Family: Pinaceae

Genus: Abies (Firs)
Genus: Larix (Larches)
Genus: Picea (Spruces)
Genus: Pinus (Pines)
(Western Yellow Pine)
Idaho White Pine
(Western White Pine)
Genus: Pseudotsuga (Douglas Fir)
Genus: Tsuga (Hemlock)

Family: Pinaceae (Pines)
    Most plants in this family found in Idaho are trees. Stunted alpine plants may be deformed shrubs [krumholtz]. Singleleaf pinyon pine sometimes appears to be a shrub. Males cones are small, soft, short-lived, falling off after shedding their pollen. Idaho plants have two elongate anther sacs on each stamen which are borne on the lower surface (referred to as dorsal or abaxial side) of each scale. The scales are spirally arranged on each cone. Female or seed bearing cones are mostly large and woody. Each cone bears numerous, spirally arranged scales. Each scales bears 2 inverted ovules on the upper (adaxial) surface. Each scale is subtended by a bract which may be variously modified and either free or fused (adnate). The scales may be persistent after the cones fall from the tree or may be individually deciduous as in firs (genus Abies). The seeds are winged. Each seed has 2-15 cotyledons (seed leaves). Idaho trees have both pollen and seed cones on each tree (monoecious).

The branches are mostly whorled. The spirally arranged leaves are needle-like. Most are persistent, but the larch (genus Larix)loses its leaves each fall. The needles are born singly (most), but in some (genus Pinus except for the singleleaf pinyon pine) are borne in 2's, 3's or 5's on main branches or closely aggregated and falsely whorled on short spur shoots (genus Larix )

Genus: Abies (Firs)
    The cones are borne at the tips of the previous year's branches. The males cones are pendent from the lower side of the branches mostly near the middle of the tree or above. They are 7-20 millimeters long. The stamens have knob-like tips. The seed cones are generally borne near the top of the tree, thus when the wind blows the pollen, it tends not to land in the cones of the same tree, but blows to cones of adjacent trees. The cylindric seed cones are stiffly erect and mature in one season. The numerous scales are flat, and can be either longer or shorter than their free (non-adnate) subtending bracts. The scales, bracts and seeds are shed one by one in early winter. The center stalk to which the scales were attached remains on the branch sometimes for years after the cone fell apart. Each seed has 4-10 cotyledons. The plants are tall, evergreen trees with whorled branches. The main branches branch again in one plane, forming flat sprays. The thin bark is often bulged with resin blisters (vesicles). The young bark is smooth, but generally becomes finely roughened and grayish. The needles (leaves) arise spirally from the twigs, but orient themselves into either one plane or upward. They are flat, and either blunt or slightly toothed (emarginate) at the tip. A few may be pointed, but are not pungent as spruce needles. The upper surface (adaxial side) of the needles is green, but the lower surface appears whitish. With magnification this can be seen as two white lines of stomata. The needle narrows near the base to appear like a leaf stalk (petiole). The point of attachment is circular and when the leaf falls, a circular scar is left on the twig. Grand Fir (Abies grandis (Dougl.) Forbes), White Fir (Abies concolor (Gord. & Glend.)) , and Subalpine Fir (Abies lasiocarpa (Hook.) Nutt.) grow in Idaho.

Genus: Larix (Larches)
    Cones and needles are borne on the ends of lateral spur branches; the yellowish seed cones are cylindric 3 to 4 ½ centimeters long in Idaho specimens, maturing in one season, generally red until they mature. The scales are persistent, subtended and exceeded in length by the visible, thin, long pointed (caudate), acute to retuse bracts; seeds with a thin, cuneate wing; cotyledons 5-7; leaves consisting in part of thin, scale-like, more or less hairy (tomentose), persistent bracts at the tips of short, spur-like side branches and at the base of the cones, but mostly greenish needles that are deciduous each fall, these either spirally arranged and strongly decurrent as on seedling stems and lead shoots of older plants, or crowded in false whorls of 15-40 at the tips of short, slow- growing, stubby spur-shoots. There are two species native to Idaho. A European species, Larix decidua is sometimes cultivated.

Genus: Picea (Spruces)
    Cones borne on year-old twigs, 1 to 2 cm long, yellow to purple pollen cones are pendent; the woody, thin scaled, non-prickly seed cones in Idaho specimens are cylindric, pendent, maturing in one season. The entire cone falls in the fall. The thin, narrow bracts are much shorter than the scales and are thus concealed; the strongly winged seeds are two per scale on the adaxial surface; the seeds have 4-15 cotyledons; The trees are evergreen with spirally arranged needles which may be up to 14 years old before falling off. Idaho species include Engelmann spruce (Picea engelmannii Parry, White Spruce ( Picea glauca (Moench) Voss, Colorado Blue Spruce ( Picea pungens Engelmann).

Genus: Pinus (Pines)
    Leaves of 2 kinds, the green and linear needles generally 3 to 25 cm long arranged in clusters of 2, 3, or 5 (one species Whitebark Pine has needles borne singly, but with scales in a whorl at the base of each needle), the other type of leaf (DOES NOT LOOK LIKE A LEAF!) is membranous, scale-like, forming a sheath around the bases of the leaf clusters; Pollen cones 1-many clustered at or near tip of current season's growth; Seed cones clustered at the base of current season's growth, requiring two years to mature, hard, woody, usually deciduous, but sometimes remaining on tree for many years, scales flattened becoming more or less broadened & thickened toward tip; the exposed portion (apophysis)which has a terminal or subterminal scar-like protuberance (umbo) that in some species extends into a sharp spine ; the bracts are shorter than the scales and adherent to them; The seeds may be wingless or have a terminal wing longer and wider than the seed itself; Cotyledons may be numerous, but usually number 3-15.

Genus: Pseudotsuga (Douglas Fir)
    One species in Idaho Pseudotsuga menziesii (Mirbel) Franco.; up to 90 Meters tall with thick, rough, dark brown bark; leader erect; needles vary in length from 1.5 to 3.5 cm long, flat, usually uniformly spreading, more white on abaxial side due to lines of stomata; seed cones 4-10 cm long, different from all other Idaho conifers in that there are 3 pointed bracts protruding from between the scales; bracts are green when cones are maturing, but become brown as the scales after cones fall; seeds 5-6 mm long with wings 10 to 12 mm long; trees are found throughout Idaho; this may be the most valuable timber tree in the United States.

Genus: Tsuga (Hemlock)
    Seed Cones borne on last year's growth mostly restricted to upper part of the tree, 1.5 to 7 cm long; Pollen cones at twig tips varying in color from green to purplish; seeds nearly surrounded by their wings; needles flat, whitish on abaxial side, may becoming 2-ranked by twisting of the petiole; trees are characteristic by the drooping top leader.

Key to Family:
1a. Needles deciduous, 10-30 apparently in a whorl terminally on short branches or spurs Larches ( genus Larix)
1b. Needles not deciduous, never more than 5 in a cluster or borne singly
2a. Needles surrounded at base by a papery sheath of bracts, 1-5 per cluster; seed cones relatively hard, sometimes with prickles on the end of each scale, require two years to mature Pines (Genus Pinus )
2b. Needles borne singly and spirally arranged along the twigs, no sheath at their bases; seed cones relatively soft, never with prickles at the scale ends, mature in one year
3a. Seed cones erect at maturity, seeds released by disintegration of cones (deciduous scales leaving cone center stalk erect on tree); needles flat, blunt tipped & slightly stalked at their bases Firs ( Genus Abies)
3b. Seed cones pendant at maturity, shed entire, seeds commonly released by scales spreading rather than falling off the center stalk; needles flat or quadrangular
4a. Seed cones with 3-pronged bracts protruding from between scales; branchlets not markedly roughened;
dormant, terminal buds reddish-brown, pointed Douglas Fir ( Genus Pseudotsuga )
4b. Seed cones without 3-pronged bracts protruding from between scales; branchlets with small persistent protuberance remaining after needles have dropped off, branchlets thus markedly roughened; terminal buds various
5a. Needles square or 4-cornered in cross-section, sharp pointed (pungent), narrowed gradually toward base, not slenderly petiolate, rather uniformly colored adaxially and abaxially; tree top erect
Spruces (Genus Picea )
5b. Needles flat, blunt, abruptly narrowed to a short, slender petiole, abaxial surface often much whiter than adaxial surface; tree top usually drooping Hemlocks (Genus Tsuga ) KEY TO IDAHO SPECIES (Fir)
1a Tree shape is a blunt-pointed at the top; Leaves blunt or retuse, white stomatous only on the lower surface, green on the upper surface: Leaves horizontally spreading, upper surface of twigs bare except for twisted leaf bases; resin canals less than 1/4 as broad as the midvein of the leaf and located near the lower epidermis of the leaf less than half the distance between the margins and the midvein; Seed cones light green, 6-12 centimeters long, bracts much shorter than the scales, thus concealed from the outside of an intact cone; trees can be up to 90 meters tall and grow at elevations from sea level up to 7000 feet in the Rocky Mountains; Distribution Vancouver Island, mainland British Columbia, south to California east to Southeast British Columbia , Idaho, Montana, and Northeast Oregon. Other common names are Lowland Fir, Lowland White Fir, Lowland Silver Fir, Lowland Balsam Fir.
Grand Fir (Abies grandis (Dougl.) Forbes)
1b Tree shape is church-spire pointed rather than blunt-pointed; Leaves often acute, white on both surfaces with lines of stomata; With the exception of white fir, tending to spread upward or to spread more nearly in all directions rather than mainly horizontally; resin canals usually larger, up to half as broad as the midvein and located medianly between the upper and lower epidermis and between the leaf margins and midvein.
2a Needles flat, 3-4 times as broad as thick, 3-4 centimeters long, generally spreading horizontally, the upper surface of the branchlets mostly exposed; resin ducts small, near leaf edges (margins) less than 1/3 the distance between margins and midvein and just within the lower epidermis; young twigs often without hairs (glabrous) and shining; 5-10 centimeter long, yellow to brownish or greenish purple cones without visible bracts; trees can be up to 80 meters tall. Distribution from northeastern Oregon to much of California, Nevada, and Arizona to Baja California, east to western Wyoming and south to Northern Mexico, from the Oregon Cascades to Mount Jefferson, & in the Oregon and Washington Blue Mountains and Adjacent Idaho at low elevations in the mountains . Other common names: Balsam, White balsam or silver fir. Often intergrades with grand fir.
White Fir Abies Concolor (Gord. & Glend. ) Lindl.
2b. Needles much the thickest in center, mostly less than 3 times longer than thick, generally less than three centimeters long tending to turn upward more than to spread horizontally; resin ducts located 1/3 to ½ as broad as the midvein, midway between the upper and lower epidermis; young twigs finely pubescent; 6-11 cm long, mostly purple cones without visible bracts; tree up to 30 meters tall, but often dwarfed and shrub-like; Distribution- subalpine to alpine slopes from 2500 feet elevation upward to timberline from Alaska and Yukon south to Southern Oregon in both Cascades and Olympic Mountains east to central Idaho and Montana and south to New Mexico and Arizona. Other common names are Alpine, Balsam, or White Balsam Fir.
Subalpine Fir Abies lasiocarpa (Hook.) Nutt.KEY TO IDAHO LARCH SPECIES
1a Young branches strongly hairy (tomentose) with long, tangled hairs; needles about as thick as broad, generally showing 2 small resin ducts in cross-section under 25 power magnification; seed cones 3-4.5 centimeters long; small, subalpine or alpine trees which are 10 to 15 (rarely 25) meters tall, generally near timberline, often on north facing slopes; distribution southern British Columbia to central Cascade and Wenatchee Mountains, Washington, east to southwestern Alberta, north Idaho, and western Montana. Other common names Subalpine or Lyall Larch, tamarack
Alpine Tamarack Larix lyallii Parl.
1b Young branches without hair (glabrous) to somewhat pubescent, if so the hairs short and not tangled; needles much broader than thick, nearly plane on upper surface but strongly ridged beneath and broadly triangular in section, without visible resin ducts; seed cones 2.5 to 3 ½ centimeters long; large trees up to 80 meters tall; distribution - from foothills to mid montane, rarely subalpine, often where swampy; southern British Columbia south, east of Cascades, to Deschutes County, Oregon, east to Northern Idaho and northeastern Oregon; other common names Western Larch, Montana Larch, Mountain Larch, Hackmatack, Tamarack, Western Tamarack.
Western Larch Larix occidentalis Nutt.Key to Spruces of Idaho
1a. Young branches hairy (pubescent) needles 4 angled; seed cones less than 6 cm long, scales triangular in shape, with toothed edges. Engelmann Spruce (Picea engelmannii Parry)
1b. Young branches without hair (glabrous); needles and seed cones various
2a. Seed cones mostly 2.5-3.5 cm long with rounded scales (like one's thumb nail)
White Spruce (Picea glauca (Moench) Voss)
2b. Seed cones more than 4 cm long with pointed triangular scales or elongate scales blunt at tip
3a. Seed cones less than 6 cm long with triangular scales; needles not sharp pointed.
Engelmann Spruce (Picea engelmannii Parry)
3b. Seed cones more than 6 cm long, scales elongated, usually curved upward at tips, tips often blunt or notched; needs very sharp - pointed.
Blue Spruce (Picea pungens Engelm.)KEY TO THE IDAHO SPECIES OF PINES
1a. Needles borne singly (rarely 2), scale sheath deciduous; tree up to 15 meters tall, but usually low, sprawling; Seed cones up to 6 cm long, depressed ovoid; seeds12-15 mm long, edible; southern Idaho only.
Singleleaf Pinion Pine (Pinus monophylla T. & F.)
1b. Needles born in cluster of 2-5, scale sheath persistent; trees 60 meters tall, habit , seeds, cones various; range not limited to southern Idaho
2a. Needles borne in clusters of 5
3a. Seed cones purplish, ovoid, about as long as wide, usually remaining closed even after falling off tree, scales much thickened; trees mostly shrub-like in appearance, but up to 15 meters tall, of higher elevations
White-bark Pine (Pinus albicaulis Engelm.)
3b. Seed cones brown, opening on tree or after falling, elongate, up to 2.5 dm long; Scales various; habit erect, tree-like
4a. Mature, fresh cones very resinous, tan in color, usually 8 cm long; scales not much thickened, seeds 10-12 mm long, wings shorter than the seed; trees normally of higher elevations, but also found at Craters of the Moon; branchlets extremely limber
Limber Pine (Pinus flexilis James )
4b. Mature, fresh cones not obviously resinous, light brown in color, curved, usually 8 cm long, but up to 2 ½ dm long; scales thin, seeds 8 mm long with wings 2-3 times longer than the seed; central Idaho and northward; tall trees up to 40 meters
Idaho state tree Idaho White Pine, Western White Pine (Pinus monticola Dougl.)
2b. Needles in clusters of 2 or 3
5a. Leaves 2 in a fascicle, 3-6 cm long, twisted; seed cones asymmetrical at base, 4-6 cm long
Lodgepole pine (Pinus contorta Dougl.)
5b. Leaves mostly 3 in a fascicle intermixed with some 2 in a fascicle, 12-25 cm long; seed cones leave base of cone on tree when falling off, cones usually 8-10 cm long; tree has an orangish bark
Ponderosa or Western Yellow Pine (Pinus ponderosa Dougl.)KEY TO IDAHO HEMLOCKS (Genus Tsuga)
1a. Cones 2-3 cm long with 12-20 scales; drooping branchlets slender; needles flat and whitish beneath; habitat usually below 5000 feet elevation; restricted to northern Idaho
Western Hemlock (Tsuga heterophylla ( Raf.) Sarg.
1b. Cones 4-7 cm long with numerous scales; branches slightly if at all drooping; needles somewhat thickened in the middle and more or less 4 sided, stomata equal adaxially and abaxially; habitat subalpine and alpine, may be dwarfed at high elevations; restricted to northen Idaho
Mountain hemlock (Tsuga mertensiana (Bong.) Carr.

Information by Dr.Karl E. Holte, ©2001.