| Chinese hemlock | |
|---|---|
| |
Scientific classification 
| |
| Kingdom: | Plantae |
| Phylum: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Tsuga |
| Species: | T. chinensis
|
| Binomial name | |
| Tsuga chinensis | |
Tsuga chinensis, commonly referred to as the Taiwan or Chinese hemlock, or in Chinese as tieshan (simplified Chinese: 铁杉; traditional Chinese: 鐵杉; pinyin: tiěshān; lit. 'iron fir'), is a coniferous tree species native to China, Taiwan, Tibet and Vietnam. The tree is quite variable and has many recognised varieties, though some are also maintained to be separate species by certain authorities. The tree was recently discovered in the mountains of northern Vietnam, making that the southernmost extension of its range.
Tsuga chinensis is a large tree with bark that is a blackish brown in colour. The scaly bark has irregular longitudinal breaks, and lenticels that are very inconspicuous. The outer bark is about 6 mm thick with alternating tiered layers of pale yellowish brown corky bark, and brown lignified fibrous bark. The newly formed periderm is a purplish red. The inner bark is about 4 to 5 mm (0.16 to 0.20 inches) thick and pale reddish brown in colour. It is fibrous in texture with minute, almost inconspicuous sclereid, or stone cell groups. The cambium as well as the newly formed phloem are nearly inconspicuous. Freshly cut wood is a pale yellowish white with inconspicuous wood rays.[2]
The branchlets that have leaf-cushions. The leaves are arranged spirally in a manner more or less 2-ranked. They are linear and flat in shape and olive green in colour. The upper side of the leaf is grooved and keeled, while the underside has 2 white stomatic bands. The apex of the leaves are emerginate and they measure 16 to 20 mm (0.63 to 0.79 inches) long. The petioles are crooked. The foliage is very similar to that of T. heterophylla, but T. chinensis has nodding shoots and the stomatic bands are paler and more sparse. Also the colour above is a paler yellowish-green.[3] The stamenate flowers appear singly on one-year-old shoots, or in groups of 1 to 5 on two-year-old shoots. They are a dull purple in colour and measure about 8 mm (0.31 inches). The pistillate flowers are terminal on a very short shoot. They nod, are rosy-purple and are about 6 mm (0.24 inches) in length. The mature cones are green, later turning to red-brown, long-ovoid in shape and measure 2 to 2.5 mm (0.079 to 0.098 inches) long by about 1 cm (0.39 inches) wide. They are pendulous and the cone scales are large and suborbicular with longitudinal streaks. The bracts are small and 2 lobed at the apex. The seeds are winged and measure about 7 mm (0.28 inches) long with the wing included.[2][3]
The range of T. chinensis begins in the west in Tibet and continues east into China, north to southern Shanxi province and south to Guangdong province, Taiwan and the north of Ha Giang province in northern Vietnam. In the very south of their range they are only found high in the mountains. For example, in Vietnam the tree is only found in mountains 1,300 to 1,700 m (4,300 to 5,600 feet) above sea level.[4][5] In China it is present at altitudes of 1,000 to 3,500 m (3,300 to 11,500 feet) in the following provinces: Anhui, Fujian, southern Gansu, Guangdong, Guangxi, northern Guizhou, western Henan, western Hubei, Hunan, Jiangxi, southern Shaanxi, Sichuan, Xizang, Yunnan, and Zhejiang. This comprises the southern half of the country with a few population farther north. It is found primarily in mixed forests near river basins and in mountains and valleys.[4] In Taiwan it is found mainly in Nantou County and Taoyuan City at heights of 1,700 to 3,500 m (5,600 to 11,500 feet) in mixed broadleaf forests. It can be found in Taiwans's Yushan National Park and Lalashan Preserve, as well as in China's Hailuogou Glacier Park in Sichuan province.[6]
There are a number of varieties of T. chinensis, though there is much dispute over which are valid and whether some constitute distinct species or not. All in all there are six varieties, though not all are accepted universally. These are:
The timber obtained from T. chinensis is used in construction, furniture making, and as a support in mines. The bark is high in tannins, which is often extracted and used as a dye. The trunk is used as a source of resin. In addition, the roots, trunk, and branches are all used in the production of aromatic oils due to their pleasing scent.[4]
