Pinus kwantungensis, first described in 1948 by Woon Young Chun (1890–1971) et Ying Tsiang (1898–1982), is commonly known as Guangdong white pine; as well as Thông Pà cò in the Vietnamese language; and 华南五针松 (huanan wuzhen song) in Chinese. The species name recognizes Guangdong province in China.
Many authors do not treat it at the species rank, preferring to lump it with either of the closely related taxa Pinus morrisonicola of Taiwan or Pinus fenzeliana of south China and Vietnam.
Ethnobotany. Timber is used by local people as good construction timber. Besides this, its oleo resin can be used as an adhesive. This is a very endangered tree species of Vietnam. Due to its confined habitats, the number of individuals is not many, and the needs in construction timber and fuel wood of the tribesmen groups may cause the species to disappear; its number being strongly reduced. Rated as a vulnerable species. We need integral protection of the species in-situ (at the existing pine groves of Pa Co). Research should also be made to create plantations of the species at its range of habitats, as supplementary measures for preservation.
Description. Hunan white pine is an evergreen coniferous species of tree that grows to mature heights of 100 feet (30 m); with a trunk up to 60 inches (150 cm) in diameter, measured at breast height.
Bark is brown and scaly.
Branchlets are pale brown in the first year; old branchlets are grayish brown or yellow-brown, and glabrous, rarely puberulent.
Foliar buds are colored black to brown and slightly resinous.
Leaves (needles ) are borne in bundles of 2 to 5 per fascicle. They are triangular in cross section, measuring 1.4 to 2.8 inches (3.5 - 7 cm) long by 0.04 to 0.06 inch (1 - 1.5 mm) thick, with 1 vascular bundle, 2 resin canals at the margins, sometimes also 1 at the medial
Seed cones are usually borne solitary on a 0.28 to 0.8 inche (7 - 20 mm) peduncle. They are red-brown at maturity, cylindric-oblong or cylindric-ovoid shaped, slightly resinous, and measure 1.2 to 3.6 (3 - 9 cm) long by 0.6 to 2.8 inches (1.5 - 7 cm) broad.
Seed scales are cuneate-obovate, measuring 1 to 1.4 inch (2.5 - 3.5 cm) by 0.6 to 0.92 inch (1.5 - 2.3 cm); apophyses have a rhombic outline, thin apex, and are straight or slightly incurved.
Seeds are ellipsoid or obovoid shaped and measure 0.32 to 0.48 inch (0.8 - 1.2 cm), with wing subequal to seed scales. Pollination takes place in Apr and May; seed matures in October of the second year after pollination.
Pinus wangiiof Yunnan and Vietnam is similar, but has densely pubescent branchlets and 3 medial resin canals, while P. kwangtungensis has glabrous (rarely puberulent) branchlets and 2 marginal resin canals (sometimes also 1 medial).
Distribution. This species is native to China — in northern Guangdong, southwestern Guangxi, southern Guizhou, Hainan, and southern Hunan provinces, where it occurs altitudes of 1,600 to 5,200 feet (500 - 1,600 m) above sea level. It is possible that the Hainan collections actually represent the closely related P. fenzeliana.
In Vietnam, it is found in Hoa Binh (Pa Co commune, Mai Chau district) and Cao Bang (Duc Hong commune, Trung Khanh district), on limestone peaks at elevations of about 4,200 to 5,000 feet (1,300 - 1500 m) above sea level. It grows in pure stands, or mixed with Chamaecyparis hodginsiiand some species of Fagaceae and Lauraceae.
Hardy to USDA Zone 9 — cold hardiness limit between 20° and 30°F (-6.6° and -1.1°C).