Chinese hemlock (Tsuga chinensis)

Description

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; literally: "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 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. 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 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. 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. The pistillate flowers are terminal on a very short shoot. They nod, are rosy-purple and are about 6 mm in length. The mature cones are green, later turning to red-brown, long-ovoid in shape and measure 2 to 2.5 cm long by about 1 cm 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 long with the wing included.