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Metasequoia Miki ex Hu et Cheng

水杉属

Description from Flora of China

Trees deciduous, monoecious; main branches irregularly whorled; branchlets of several kinds: persistent or deciduous, opposite or subopposite, developing from paired, superimposed axillary buds, 1 of which remains dormant as a winter bud; winter buds ovoid or ellipsoid, with 6-8 pairs of decussate, ovate, membranous, scales; branchlets each subtended by ca. 4 whorls of early deciduous, salmon-colored basal scales. Leaves deciduous together with lateral branchlet as a unit, decussate, 2-ranked, spirally arranged on leading branchlets, ± sessile; blade linear, flattened, soft, midvein depressed adaxially, raised abaxially, stomatal bands 4-8, on abaxial surface only, or on both surfaces on seedling leaves, base twisted. Pollen cones developing in autumn but not shedding pollen until following spring, borne in spikes or panicles, shortly pedunculate; microsporophylls 15-20, decussate, each with 3 pollen sacs, except apical and basal with 2. Seed cones terminal or subterminal on previous year’s growth, solitary, shortly pedunculate at pollination, becoming long pedunculate and pendulous, subglobose, slightly cubic, or occasionally oblong-globose, ripening in 1st year; peduncle clothed with decussate, linear leaves; cone scales 16-24, persistent, decussate, shieldlike, woody, grooved, 5-9-seeded (when fertile), base cuneate, distal part transversely rhombic. Seeds 5-9, compressed-obovoid, winged all round, apex emarginate. Cotyledons 2. Germination epigeal. 2n = 22*.

* One species: China.

A relict species of the Cretaceous and Cenozoic, when this genus was widely distributed in what is now NE China, Europe, Greenland, Japan, North America, and Russia (Siberia).

孑遗植物区 Rare Plants Area, 裸子植物区 Gymnosperm Area, 濒危园 Endangered Plants Garden

Lower Taxon


 

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