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6. Tsuga (Endlicher) Carrière, Traité Gen. Conif. 185. 1855.

铁杉属 tie shan shu

Pinus Linnaeus sect. Tsuga Endlicher, Syn. Conif. 83. 1847; Nothotsuga Hu ex C. N. Page.

Trees evergreen; branches irregularly whorled; branchlets with leaf cushions and persistent winter bud scales at base; winter buds ovoid or globose, not resinous. Leaves pectinately arranged, rarely radially spreading (emerging in false whorls on lateral branchlets), petiolate; petiole twisted at base; blade usually linear and flattened, stomatal lines abaxial, rarely on each surface, in 2 white bands, separated by an elevated midvein, vascular bundle 1, resin canal 1 below vascular bundle. Pollen cones growing from lateral buds, solitary, rarely clustered in umbels from a single bud, ellipsoid or ovoid; pollen with ring-shaped, saccate structure near distal pole, rarely ± 2-saccate. Seed cones terminal (rarely lateral) on 2nd-year branchlets, solitary, pendulous, rarely erect, ovoid-globose to cylindric or obovoid-oblong, maturing in 1st year. Seed scales thin, woody, persistent. Bracts included, rarely with slightly exserted, apical cusp. Seeds small, with small resin vesicles adaxially. Cotyledons 3-6. Germination epigeal. 2n = 24*.

Nine or ten species: E Asia and North America: four species (three endemic) in China.

1 Leaves radially spreading (emerging in false whorls on lateral branchlets), blade with lines of stomata on each surface; pollen cones clustered in umbels from a single lateral bud; seed cones ± erect, bracts slightly exserted at apex   1 Tsuga longibracteata
+ Leaves pectinately arranged, blade with lines of stomata on abaxial surface only; pollen cones solitary; seed cones pendulous, bracts wholly included.   (2)
2 (1) Seed scales thin, slightly recurved distally; branchlets brown lanate   2 Tsuga dumosa
+ Seed scales thick, not recurved distally; branchlets not brown lanate.   (3)
3 (2) Seed scales loosely arranged, narrowly elliptic, ca. 2 × as long as wide; seed cones ovoid-cylindric or narrowly ovoid   3 Tsuga oblongisquamata
+ Seed scales densely arranged, variable in shape, as long as or only slightly longer than wide; seed cones ovoid-globose or obovoid-oblong   4 Tsuga chinensis

Lower Taxa


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