About Keteleeria davidiana (Bertrand) Beissn.
Keteleeria davidiana (Bertrand) Beissn., known as 铁坚油杉 in Chinese, is a coniferous evergreen tree. It is native to Taiwan and southeast China, where it occurs in the provinces of Gansu, Guangxi, Guizhou, Hubei, Hunan, Shaanxi, Sichuan, and Yunnan. It also grows in the far northern part of Vietnam. This species is restricted to hills, mountains, and valleys at elevations between 200 and 1500 m. Compared to the other two Keteleeria species, it generally grows in regions with a more continental climate. Mature trees reach 40–50 m in height, and develop an irregular oblate crown supported by large branches. Branchlets are densely covered in stiff hairs. The bark is dull brown to dark gray-black, with a scaly or flaky texture. The leaves are needle-like, measuring 2-6.4 cm long and 3.6-4.2 mm broad; they are flat, stiff, and dark shiny green. The cones are light brown, cylindrical, and grow erect on the branches. They measure 8–20 cm long and 4–5 cm broad, with a stalk that is 2.5-3.2 cm long. The winged oblong seeds, which mature in October or November, are 13 mm long, with a glossy brown wing 12–19 mm long. Three varieties of Keteleeria davidiana are recognized. Keteleeria davidiana var. calcarea grows on calcareous mountains in Guangxi and Guizhou; it has yellow first-year branchlets, blunt and rounded seed scale apices, and globular winter buds. Keteleeria davidiana var. davidiana has yellow-gray or light-gray first-year branchlets, narrowed seed scale apices, and ovoid winter buds. Keteleeria davidiana var. formosana is endemic to Taiwan, where it grows at 300–900 m; it has prominently protruding dark leaf scars on branches, and leaves that are 2–4 cm long. The wood of Keteleeria davidiana is soft and white-yellow, and is used for construction, bridges, furniture, and wood fiber.
