Scientific name: Thuja standishii (G. Gordon) Carrière 1867

Synonyms: Thuja gigantea var. japonica (Maxim.) Franch. & Sav., Thuja japonica Maxim., Thuja odorata Doi, Thujopsis standishii Gordon

Common names: Japanese arborvitae (English), Nezuko, Kurobe (Japanese)

Description

Tree to 20(-35) m tall, with trunk to 1(-2) m in diameter. Bark furrowed, fibrous, reddish brown, peeling in flakes or longitudinal strips, even in very young plants. Crown conical, with upwardly angled branches bearing branchlets that are less flattened than in other species. Foliage lemon-scented when crushed. Scale leaves 2-3 mm long, dark green above, with grayish white stomatal zones beneath. Facial leaves glandless. Leaves of main branchlets with short, spreading tips. Pollen cones yellow, 1-3 mm long, with four to eight pairs of pollen scales. Seed cones 8-13 mm long, with four to six pairs of scales, the middle two pairs fertile, each scale with a short point below the tip. Seeds one or two (to three) per scale, 5-7 mm long including the slightly longer wings, each wing conspicuously narrower than the body.

The species name honors John Standish (1814 - 1875), proprietor of Sunningdale Nursery in Ascot, England, to whom Robert Fortune sent seed in 1860 that he had collected in Tokyo gardens, along with seed of many other species from Japan and China.

Restricted to Japan where widespread on Honshū and Shikoku. Moist rocky mountain slopes; (250-)900-1,800(-2,500) m.

Conservation Status

Red List Category & Criteria: Near Threatened

The protected status in the historical past of this species is assumed to have had a positive effect preventing over-exploitation. However, its valuable timber must have led to some reduction in abundance of mature trees but it is uncertain if this exceeds the thresholds for listing in any threatened category. Presently, there is only limited exploitation. These circumstances lead us to flag it as Near Threatened as it is thought to be probably close to meeting the population reduction threshold under criterion A2d with between 20 and 29% population reduction over the past 75 years (three generations).

Thuja standishii occurs in mixed montane conifer or conifer-angiosperm forests, with Abies homolepis, Chamaecyparis obtusa, Chamaecyparis pisifera, Thujopsis dolabrata, Tsuga diversifolia, Picea jezoensis, Pinus parviflora, and Larix kaempferi. Common angiosperm trees are Betula ermanii, Betula corylifolia, Fagus sieboldii, Quercus mongolica var. grosseserrata, and Zelkova serrata. Thuja standishii is a minor component in these forests, usually remaining a smaller tree than the dominants and not exceeding 15 m in height. Often it is confined to moist rocky precipices facing north, sites less suitable for larger trees.

Selective logging for its valuable timber is the main threat. The wood of this species is highly prized for special building purposes, e.g. ceilings and panelling, and is also used for furniture, fanlights and clogs (wooden shoes). It was in the past regarded as one of the 'five trees of Kiso' or 'Tome-ki' (preserved trees) which meant they were the property of the Emperors of the Tokugawa dynasty in the 17th and 18th centuries and not to be used by common people. This practice preserved several forests from overexploitation. In Japan it has been used as an ornamental tree for many centuries. Robert Fortune first saw it in 1860 in gardens in Tokyo and introduced it to England via Standish's nursery at Ascot. It is still in cultivation in Europe and the USA but much less common there than some of the other species and mostly seen as specimen trees in dendrological collections.

This species is recorded from several protected areas.

References

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