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3. Larix Miller, Gard. Dict. Abr., ed. 4. 1: [744]. 1754.
落叶松属 luo ye song shu
Trees deciduous; branches irregularly whorled, spreading; branchlets strongly dimorphic: long branchlets with leaves present only in 1st year, older parts with leaves in dense tufts on lateral short branchlets developed from axillary buds. Leaves spirally arranged on long branchlets, in dense clusters of 15-50 or more on short branchlets, sessile, turning yellow and falling in autumn, linear-needlelike, flattened, longitudinally keeled adaxially, sometimes also slightly so abaxially, ca. 1.8 mm wide, flexible, stomatal lines abaxial or on each surface, vascular bundle 1, resin canals 2, usually marginal. Cones borne at apex of short branchlets, solitary. Pollen not saccate, with a narrow, equatorial ridge. Seed cones shortly pedunculate, usually erect, purplish, reddish, or rarely green, maturing in 1st year. Seed scales thin, ± leathery, opening to release seeds, persistent. Bracts included or exserted, ovate or lanceolate, midvein prominent abaxially, forming an apical cusp. Seeds small; wing persistent, relatively long, membranous. Cotyledons 6-8. Germination epigeal. 2n = 24*.
Fifteen species: boreal and temperate regions of Asia, Europe, and North America; 11 species (four endemic, two introduced) in China.
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| 1 |
Seed cones ovoid or narrowly ovoid; bracts included or slightly exserted, shorter than seed scales; branchlets not pendulous. |
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(2) |
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Seed cones cylindric or ovoid-cylindric; bracts obviously exserted, longer than or rarely equal to seed scales; branchlets pendulous. |
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(6) |
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| 2 (1) |
Seed scales triangular-ovate, ovate, or subrhombic, usually densely purplish brown hairy abaxially, apex rounded |
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7 Larix sibirica |
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Seed scales pentagonal- or quadrangular-ovate, glabrous, usually smooth and shining on exposed part abaxially, apex emarginate or ± truncate. |
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(3) |
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| 3 (2) |
Seed scales ± recurved at margin distally; 1st-year branchlets glaucous |
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11 Larix kaempferi |
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Seed scales not recurved distally; 1st-year branchlets not glaucous. |
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(4) |
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| 4 (3) |
Seed scales at middle of cones pentagonal-ovate, ± convex, longer than wide |
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8 Larix gmelinii |
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Seed scales at middle of cones suborbicular, subrectangular, or ± square, as long as or longer than wide. |
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(5) |
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| 5 (4) |
First-year branchlets reddish brown or light brown, usually sparsely to densely pubescent; seed scales 16-40, broadly square-ovate or square-orbicular; tips of bracts not exposed |
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9 Larix olgensis |
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First-year branchlets light yellow or yellowish gray, glabrous; seed scales 45-50, suborbicular; tips of bracts slightly exposed |
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10 Larix decidua |
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| 6 (1) |
Bracts straight or slightly recurved at apex. |
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(7) |
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Bracts reflexed or recurved. |
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(8) |
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| 7 (6) |
Seed cones stout; seed scales gray or yellow-gray, square-orbicular or oblong, longer than wide, apex rounded or square-orbicular |
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5 Larix himalaica |
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Seed cones relatively slender; seed scales dark brown or dark gray, square-orbicular, obtriangular-orbicular, or subsquare, as wide as or wider than long, apex truncate, emarginate, or truncate-rounded |
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6 Larix potaninii |
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| 8 (6) |
Seed cones ellipsoid-cylindric, 2.5-4 cm; seed scales obtriangular- or reniform-orbicular, densely long hairy abaxially; short branchlets densely yellow hairy; leaves 1.2-3.5 cm, keeled on both sides |
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4 Larix mastersiana |
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Seed cones cylindric, 4.5-11 cm; seed scales obovate-quadrangular or suboblong, usually densely pubescent and tuberculate abaxially; short branchlets glabrous or subglabrous; leaves 2.5-5 cm; keeled only adaxially. |
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(9) |
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| 9 (8) |
Pollen cones ovoid, 6-8 mm; short branchlets wider than long |
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3 Larix kongboensis |
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Pollen cones ovoid-conical or columnar, 10-22 mm; short branchlets as wide as long. |
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(10) |
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| 10 (9) |
Bracts obviously reflexed, obovate- or ovate-lanceolate, 5-7 mm at widest part; short branchlets slender, only bases of scales persistent |
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1 Larix griffithii |
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Bracts obliquely spreading and recurved, lanceolate, 3.5-5.5 mm at widest part; short branchlets stout, scales persistent, revolute |
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2 Larix speciosa |
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List of lower taxa
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