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5. Picea A. Dietrich, Fl. Berlin. 2: 794. 1824.
Spruce, épinette [Latin picis, pitch, name of a pitchy pine]
Ronald J. Taylor
Trees evergreen; crown broadly conic to spirelike; leading shoot erect. Bark gray to reddish brown, thin and scaly (with thin plates), sometimes with resin blisters (especially in Picea engelmannii and P . glauca ), becoming relatively thick and furrowed with age. Branches whorled; short (spur) shoots absent; twigs roughened by persistent leaf bases. Buds ovoid, apex rounded to acute, sometimes resinous. Leaves borne singly, spreading in all directions from twigs, persisting to 10 years, mostly 4-angled and square in cross section (to triangular or ± flattened), mostly rigid, sessile on peglike base; base decurrent, persistent after leaves shed, sheath absent; apex usually sharp-pointed, sometimes bluntly acute; resin canals 1--2. Cones borne on year-old twigs. Pollen cones grouped, axillary, oblong, yellow to purple. Seed cones maturing in 1 season, usually shed at maturity (persisting for several years in Picea mariana ), borne mostly on upper branches, pendent, ovoid to cylindric, sessile or terminal on leafy branchlets and thus appearing ± stalked; scales persistent, elliptic to fan-shaped, thin, lacking apophysis and umbo; bracts included. Seeds winged; cotyledons 5--l5. x =12.
Species ca. 35 (8 in the flora with 7 native and 1 naturalized): north temperate regions, North America, Mexico, Eurasia.
SELECTED REFERENCES Roche, L. 1969. A genecological study of the genus Picea and seedlings grown in a nursery. New Phytol. 68: 505--554. Taylor, R.J. and T.F. Patterson. 1980. Biosystematics of Mexican spruce species and populations. Taxon 29: 421--469. Wright, J.W. 1955. Species crossability in spruce in relation to distribution and taxonomy. Forest Sci. 1: 319--349.
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| 1 |
Leaves flattened or broadly triangular in cross section; stomates occurring only on, or more conspicuously on, adaxial leaf surface; Alaska to California. |
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(2) |
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Leaves square in cross section; stomates occurring more or less equally on all leaf surfaces; widespread. |
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(3) |
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| 2 (1) |
Leaf apex sharp-pointed; twigs glabrous; seed-cone scales elliptic to narrowly diamond-shaped. |
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7 Picea sitchensis |
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Leaf apex blunt, especially on older leaves; twigs finely pubescent; seed-cone scales fan-shaped. |
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8 Picea breweriana |
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| 3 (1) |
Twigs pubescent; cone scales usually fan-shaped, broadest near apex; seed cones 2.3-4.5(-5) cm; mostly eastern or boreal. |
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(4) |
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Twigs mostly glabrous; cone scales usually ± diamond-shaped or elliptic, broadest near middle (broadest at apex in Picea glauca); seed cones (2.5-)3-16 cm; mostly western or boreal. |
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(5) |
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| 4 (3) |
Seed cones 1.5-2.5(-3.5) cm; leaves 0.6-1.5(-2) cm, mostly blunt-tipped, glaucous, blue- to gray-green. |
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2 Picea mariana |
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Seed cones 2.3-4.5(-5) cm; leaves 0.8-2.5(-3) cm, mostly acute, sharp-pointed, not glaucous, yellow-green to dark green. |
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3 Picea rubens |
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| 5 (3) |
Seed cones (10-)12-16 cm; leaves 1-2.5 cm, blunt-tipped; introduced and locally naturalized species. |
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1 Picea abies |
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Seed cones 2.5-11(-12) cm; leaves (0.8-)1.2-3(-3.5) cm, mostly sharp-pointed; native species. |
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(6) |
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| 6 (5) |
Seed-cone scales fan-shaped, margin at apex q entire, apex extending 0.5-3 mm beyond seed-wing impression; leaves (0.8-)1.5-2(-2.5) cm. |
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4 Picea glauca |
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Seed-cone scales diamond-shaped or elliptic, margin at apex irregularly toothed to erose, apex usually extending 3 mm or more beyond seed-wing impression; leaves 1.2-3(-3.5) cm. |
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(7) |
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| 7 (6) |
Seed cones 3-7(-8) cm; cone scales extending 3-8 mm beyond seed-wing impression; twigs finely pubescent. |
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5a var. engelmannii |
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Seed cones (5-)6-11(-12) cm; cone scales extending 8-10 mm beyond seed-wing impression; twigs usually glabrous. |
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6 Picea pungens |
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Lower Taxa
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