Tsuga dumosa

(D. Don) Eichler (1887)

Common names

Himalayan hemlock, Yunnan tieshan (Farjon 1990), Thiêt sam (FIPI 1996).

Taxonomic notes

Synonymy: see POWO for the 27 synonyms, none in common use except that some Chinese authors may recognize subspecies or varieties. Molecular evidence indicates that this widespread species of the Himalaya and the Daxue Shan shares a good part of its mitochondrial genome with T. forrestii and T. chinensis from the eastern Himalaya area, supporting the hypothesis of incomplete lineage sorting between these three taxa whose phylogeny has been linked to the development of the Qinghai-Tibetan Plateau and the rise of the Himalayas (Cun and Wang 2015, Feng et al. 2021). See also the discussion of molecular findings on the Tsuga page.

Description

Tree 20-25(-40) m high and 40-50(-100) cm dbh. Bark greyish brown, fissured. Branches oblique or horizontal; crown pyramidal. First year twigs are reddish brown or greyish yellow, covered with short hairs, 2-3 years old branches greyish brown or dark grey with leaf scars. Leaves spirally arranged on branches, linear, 10-25 mm long and 2-2.5 mm wide, obtuse or rounded, rarely emarginate, upper surface green and shiny, lower surface with 2 wide bands of stomata; upper half part with small dents (rarely entire). Midrib concave on upper surface. Male cones globose, solitary and axillary, green-yellow anthers without air sac. Female cones round-ovate, solitary and terminal, slightly down curved, with many spiral scales and 2 ovules inside each scale. Seeds with thin wing in upper parts, 9 mm long, ovate, brown. Flowering in April-May, fruiting in October-November. Wood brownish yellow, structure fine and veins straight (FIPI 1996). See also Wu and Raven (1999). See García Esteban et al. (2004) for a detailed characterization of the wood anatomy.

Distribution and Ecology

Himalaya: India from Uttar Pradesh to the Assam Himal (Arunachal Pradesh); N Burma; Viet Nam; SE Tibet; China: NW Yunnan and into SW Sichuan (Farjon 1990). In Viet Nam it is only found on Hoang Lien Son mountain, at altitudes above 1500 m. It occurs in areas with a cold climate with high rainfall, clouds and high humidity. In Viet Nam, it is usually mixed with Rhododendron spp. and Abies pindrow, but sometimes forms a pure stand (FIPI 1996). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).

Remarkable Specimens

A photograph of a specimen 320 cm dbh growing in Yunnan near Tibet appears in Pakenham (1997). Hooker (1834) reports a height of "above 120 feet" (36.6 m) for trees growing east of Lachung, Sikkim.

The oldest known living specimen, 1007 years, was documented in a tree-ring chronology covering the period 933-1996 (fully crossdated), collected near Lukuchi Khola, Nepal by Paul Krusic, Ed Cook, and Brendan Buckley (doi.org/10.25921/thdb-7m76).

Ethnobotany

Used for construction and furniture. Bark rich in tannin, that can be used for dyeing (FIPI 1996).

It has been used for dendrochronology in one exploratory study (Bhattacharyya et al. 1992).

Observations

No data as of 2023.11.06.

Remarks

The epithet dumosa is a Japanese common name for hemlock, but not referring to this species.

Citations

Bhattacharyya, Amalava, Valmore C. LaMarche Jr., and Malcolm K. Hughes. 1992. Tree-ring chronologies from Nepal. Tree-Ring Bulletin 52: 59-66.

Cun, Y.-Z., and X.-Q. Wang. 2015. Phylogeography and evolution of three closely related species of Tsuga (hemlock) from subtropical eastern Asia: further insights into speciation of conifers. Journal of Biogeography 42:315–327. https://doi.org/10.1111/jbi.12421.

Eichler 1887. P. 80 in A. Engler and K. Prantl, Die natürlichen Pflanzenfamilien 2(1). Available: Real Jardin Botanico, accessed 2022.12.24.

Farjon, Aljos. 1990. Pinaceae: drawings and descriptions of the genera Abies, Cedrus, Pseudolarix, Keteleeria, Nothotsuga, Tsuga, Cathaya, Pseudotsuga, Larix and Picea. Königstein: Koeltz Scientific Books.

Feng, Yuan-Yuan, Ting-Ting Shen, Cheng-Cheng Shao, Hong Du, Jin-Hua Ran, and Xiao-Quan Wang. 2021. Phylotranscriptomics reveals the complex evolutionary and biogeographic history of the genus Tsuga with an east Asian-North American disjunct distribution. Molecular Phylogenetics and Evolution 157:107066. https://doi.org/10.1016/j.ympev.2020.107066.

Hooker, Joseph Dalton. 1854. Himalayan journals. London: J. Murray. 2 vols (V. 2, p. 108). Available: Biodiversity Heritage Library, accessed 2019.03.09.

Pakenham, T. 1997. Meetings with remarkable trees. Random House. Page 9.

See also

Cheng and Fu (1978).

Elwes and Henry 1906-1913 at the Biodiversity Heritage Library (as T. brunoniana) (Photo). This series of volumes, privately printed, provides some of the most engaging descriptions of conifers ever published. Although they only treat species cultivated in the U.K. and Ireland, and the taxonomy is a bit dated, still these accounts are thorough, treating such topics as species description, range, varieties, exceptionally old or tall specimens, remarkable trees, and cultivation. Despite being over a century old, they are generally accurate, and are illustrated with some remarkable photographs and lithographs.

Farjon (2010).

Hiep et al. 2004.