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5. Pseudotsuga Carrière, Traité Gen. Conif., ed. 2. 1: 256. 1867.

黄杉属 huang shan shu

Trees evergreen; trunk straight; branches irregularly vertical; branchlets with slightly raised, circular leaf scars; short branchlets absent; winter buds ovoid or fusiform, not resinous. Leaves spirally arranged, ± linear, flattened, longitudinally grooved adaxially, stomatal lines abaxial, in 2 white bands, separated by an elevated midvein, vascular bundle 1, resin canals 2, sublateral, marginal, base ± twisted. Pollen cones axillary, solitary, cylindric; pollen not saccate, globose. Seed cones developing from axillary buds near ends of 2nd-year branchlets, solitary, pedunculate, pendulous, purplish red or green, maturing in 1st year. Seed scales variously shaped, convex, woody, margin rounded toward apex, persistent. Bracts well developed, exserted or included, 3-lobed, straight or reflexed, with a cusp longer than lateral lobes. Seeds borne in a shallow, membranous cup covering 1 side of seed, adnate to wing; wing obliquely ovate, short, covering only a small portion of seed scale. Cotyledons 5-8(-12). Germination epigeal. 2n = 24 (26 in P. menziesii).

Six species: China, Japan, W North America; five species (three endemic, two introduced) in China.


1 Leaf apex acute, acuminate, or obtuse; bracts appressed or reflexed.   (2)
+ Leaf apex emarginate; bracts reflexed.   (3)
       
2 (1) Seed cones ca. 8 × 3.5-4 cm; seed scales about as long as or longer than wide   5 Pseudotsuga menziesii
+ Seed cones 9-13(-18) × 4-6 cm; seed scales distinctly wider than long   4 Pseudotsuga macrocarpa
       
3 (1) Leaves 2.8-5.5 cm × 1.3-1.8(-2) mm; seed scales at middle of cones suborbicular or rhombic-orbicular; cusp of bracts 6-12 mm; wing of seeds as long as seed scale   1 Pseudotsuga forrestii
+ Leaves 0.7-2.5(-3) cm × 2-3.2 mm; seed scales at middle of cones flabellate, reniform, semiorbicular, or compressed orbicular-rhombic; cusp of bracts 2-5 mm; wing of seeds 1/2-4/5 as long as seed scale.   (4)
       
4 (3) Leaves usually (1.3-)2-2.5(-3) cm × ca. 2 mm; seed scales at middle of cones semiorbicular, flabellate, or reniform   2 Pseudotsuga sinensis
+ Leaves usually 0.7-1.5(-2) cm × 2-3.2 mm; seed scales at middle of cones broadly compressed orbicular-rhombic   3 Pseudotsuga brevifolia

Lower Taxa


 

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