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Thuja sutchuenensis

Thuja sutchuenensis


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Product Information

Scientific name: Thuja sutchuenensis Franchet  1899

Synonyms: -

Common names:Sichuan thuja, Sichuan arborvitae, Ya bai (Chinese)



Shrub, or tree to 10(-20) m tall, with trunk to 0.3 m in diameter. Bark bright reddish brown to grayish brown, fibrous, furrowed, peeling in short, curly flakes. Crown narrowly conical, with horizontal to upwardly angled, dense, slender, widely spreading branches bearing horizontal to slightly drooping branchlets. Scale leaves 1.5-4(-9) mm long, shiny bright green, with greenish white stomatal markings beneath. Facial leaves without a surface gland but with an internal resin cavity. Leaves of main branchlets with blunt, spreading or tight tips. Pollen cones 2-3 mm long, with three to five pairs of pollen scales, yellowish brown. Seed cones 5-8 mm long, with four or five pairs of seed scales, of which the middle two or three are fertile, each scale with a bluntly triangular point below the tip. Seeds 3-4 mm long, including the equal-length wings, each wing much narrower than the body.

Known only from a single population on the southern side of the Daba Shan (mountains) in Chongqing Municipality, formerly part of northeastern Sichuan (China). Scattered among shrubs or in the understory of mixed deciduous and evergreen hardwood forests on steep, moist slopes and ridge tops, often on limestone-derived soils; 1,000-1,500(-2,100) m.


Conservation Status

Red List Category & Criteria: Endangered

(Was listed as Extinct in the Wild (Oldfield et al. 1998) but was rediscovered in October 1999 by a regional team of botanists, not far from (or perhaps at) the locality where P.G. Farges had collected the only known specimens between 1892 and 1900. The team found individual trees growing scattered on cliffs and ridges of the deeply cleft mountain. There were no large trees, with most being small or even shrub-like because of their locations at higher altitudes and on exposed ridges. Seedlings are scarce. The more accessible trees have mostly been felled for use in home building and for making various household products. The species may also have gone through a genetic bottleneck and be facing problems of inbreeding depression. Following  its rediscovery in 1999 it was re-assessed as Critically Endangered. Further surveys since that assessment have produced more information so that a new assessment is required. Decline over the last three generations is estimated to be 80%. Its known area of occupancy is less than 100 km2 and there is no longer any evidence of continuing decline. The total population is estimated to be between 5,000 and 7,000 mature individuals. On the basis of this information, this species no longer meets the criteria for listing as Critically Endangered. However it does meet the criteria for listing as Endangered under A1 where the causes of the decline are understood, have ceased and are likely to be reversible. It is hoped that due to the rapid response by the Chinese authorities this species will be able to make a recovery over the coming years)



Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.

Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.

IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland


Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.

Product CodeTHUWDI8N73

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