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Taxodiaceae Warming

杉科 shan ke

Authors: Liguo Fu, Yong-fu Yu & Robert R. Mill

Metasequoia glyptostroboides
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Trees evergreen, semievergreen, or deciduous, monoecious; trunk straight; main branches ± whorled. Leaves spirally arranged or scattered (decussate in Metasequoia), monomorphic, dimorphic, or trimorphic on same tree, lanceolate, subulate, scalelike, or linear. Microsporophylls and cone scales spirally arranged (decussate in Metasequoia). Pollen cones borne in panicles, or solitary or clustered at branch apices, or axillary, small; microsporangia with (2 or)3 or 4(-9) pollen sacs; pollen nonsaccate. Seed cones terminal or borne near apex of previous year’s growth, ripening in 1st year, persistent or late deciduous; cone scales developing after ovules originate in bract axils; bracts and cone scales usually spirally aranged (decussate in Metasequoia), sessile, opening when ripe (falling in Taxodium), semiconnate and free only at apex, or completely united; bracts occasionally rudimentary (in Taiwania); ovules 2-9 per bract axil, erect or pendulous; cone scales of mature cones flattened or shield-shaped, woody or leathery, 2-9-seeded on abaxial side. Seeds flat or triangular, wingless (in Taxodium), narrowly winged all round or on 2 sides, or with a long wing on proximal part. Cotyledons 2-9. 2n = 22*.

Nine genera and 12 species: Asia, North America, and (Athrotaxis D. Don) Tasmania; eight genera (one endemic, three introduced) and nine species (one endemic, four introduced) in China.

A merger of the Taxodiaceae and Cupressaceae is increasingly supported by both morphological and molecular evidence (see note under Cupressaceae). However, the two groups are kept as separate families here for pragmatic reasons.

Tsui Hung-pin, Cheng Wan-chün, Fu Li-kuo & Chao Chi-son. 1978. Taxodiaceae. In: Cheng Wan-chün & Fu Li-kuo, eds., Fl. Reipubl. Popularis Sin. 7: 281-312.


1 Leaves and cone scales decussate (but leaves spirally arranged on leading branchlets); lateral branchlets deciduous; cone scales shieldlike, woody, 5-9-seeded (when fertile); seeds compressed, winged all round   8 Metasequoia
+ Leaves and cone scales spirally arranged (but leaves often appearing falsely 2-ranked or alternate); other characters various.   (2)
       
2 (1) Cone scales or bracts leathery.   (3)
+ Cone scales woody.   (4)
       
3 (2) Leaves linear-lanceolate, margin serrulate; bracts large; cone scales 3-seeded   1 Cunninghamia
+ Leaves scalelike or subulate, margin entire; bracts rudimentary; cone scales 2-seeded   2 Taiwania
       
4 (2) Deciduous or semievergreen; fertile cone scales 2-seeded; seeds irregularly triquetrous or slightly flattened.   (5)
+ Evergreen; fertile cone scales 2-9-seeded; seeds flattened.   (6)
       
5 (4) Deciduous or semievergreen; pollen cones borne in pendulous racemes or panicles; seeds irregularly triquetrous, large, wingless   5 Taxodium
+ Semievergreen; pollen cones borne on short, erect branchlets; seeds elliptic, slightly flattened, small, with a single, terminal, recurved wing   4 Glyptostrobus
       
6 (4) Leaves subulate; seed cones sessile; umbo of cone scales with a central spine and 4 or 5(-7) toothlike projections   3 Cryptomeria
+ Leaves all scalelike, or scalelike on main branchlets and linear on lateral branchlets; seed cones pedunculate; umbo of cone scales without spines or projections.   (7)
       
7 (6) Leaves all scalelike; seed cones with 25-40 cone scales, ripening in autumn of 2nd year   6 Sequoiadendron
+ Leaves scalelike on main branchlets and linear on lateral branchlets; seed cones with 15-20 cone scales, ripening in 1st year   7 Sequoia

Lower Taxa


 

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