Southern Japanese hemlock; ツガ tsuga, Toga matsu [Japanese].
Trees to 30 m tall and 250 cm dbh, with a usually single, straight or curved trunk and a broadly conical crown becoming irregular and often flat-topped with age. Bark dark gray, rough, scaly, forming quadrangular plates. Branchlets light grown, grey with age, barely grooved between decurrent pulvini, glabrous. Leaves of unequal length: above shoot parted, assurgent; otherwise pectinate, 10-15 × 2-2.5 mm, widest near blunt or emarginate apex, flattened, grooved above, stomata in two bands below, light green. Pollen cones 3-5 mm, crowded together, yellow. Seed cones borne on outer branches throughout crown, sessile, globose when open, (16-)20-25(-30) mm long, 14-20 mm wide, green ripening to pale brown, scales nearly round, 8-12 mm diameter; seeds 2-3 × 1.5 mm with on oblong wing 5-6 × 3 mm, light brown, tranparent (Farjon (2010).
Japan: S Honshu, Shikoku, Kyushu and Yakushima (Farjon 1990), at 500-1500 m elevation; also S. Korea, only on Ulleungdo (울릉도), a small oceanic island between Korea and Japan. Soils various, silicic; climate moist temperate, maritime, 1000-2000 mm annual precipitation. Commonly grows in mixed conifer forest; typical associates include Abies firma, Pseudotsuga japonica, Chamaecyparis obtusa, Cryptomeria japonica, Pinus densiflora, Pinus parviflora, and Sciadopitys verticillata; rarely in pure stands (Farjon (2010). Hardy to Zone 6 (cold hardiness limit between -23.2°C and -17.8°C) (Bannister and Neuner 2001).
Wilson (1916, p. 50) reports "On Yaku-shima, where the finest development of Tsuga Sieboldii is found, the trees rarely exceed 26 m. in height, but many are fully 6 m. in girth of trunk, and are picturesque in appearance."
Suzuki (1997) studied this species on Yakushima Island (屋久島). He cites his own previous work (Suzuki and Tsukahara 1987) in having found a tree stump with 794 rings on Yakushima. He also cites other previous workers as having derived ring-counted ages of 685 years on Ulleungdo (37.500°N, 130.833°E), and 639 years on Mt. Oninome, Miyazaki, Japan (32.700°N, 131.533°E).
I can find (1999.02) only two studies, both dealing with tree demography (Suzuki 1980, Suzuki and Susukida 1989).
Less common and less widely used than Tsuga diversifolia, but still used for construction, carpentry, and furniture making. A popular ornamental in Japan, it is much less common in Europe and North America (Farjon (2010).
Wilson (1916) says it is a popular ornamental in Tokyo, near its northern range limit, but is best seen on Yakushima, where it grows at 600-1500 m elevation in forests with Cryptomeria japonica and Abies firma. Most of the island is protected in Yakushima National Park, and most of the forests seen by Wilson remain intact.
Suzuki E. 1980. Regeneration of Tsuga sieboldii forest II. Two cases of regeneration occurred about 260 and 50 years ago. Japanese Journal of Ecology 30: 333-346 [in Japanese with English summary].
Suzuki E. and Tsukahara J. 1987. Age structure and regeneration of old growth Cryptomeria japonica forests on Yakushima Island. Bot. Mag. Tokyo 100:223-241.
Suzuki E. and Susukida J. 1989. Age structure and regeneration process of temperate coniferous stands in the Segire River basin, Yakushima Island. Japanese Journal of Ecology 39: 45-51 [in Japanese with English summary].
Suzuki Eizi. 1997. The dynamics of old Cryptomeria japonica forest on Yakushima Island. Tropics 6(4):421-428.
Wilson, E.H. 1916. The conifers and taxads of Japan. Publ. Arnold Arbor. 8, Univ. Press, Cambridge, Mass.
Yamanaka, T. 1975. Ecology of Pseudotsuga japonica and other coniferous forests in eastern Shikoku. Mem. Nat. Sci. Mus. 8. Tokyo.
Last Modified 2014-03-29