Pinus bhutanica

Grierson et al. 1980

Common names

Bhutan pine, Bhutan white pine; Budan Song [Chinese].

Taxonomic notes

Syn.: P. wallichiana subsp. bhutanica (Grierson et al.) Businsky 1999.

A close relative of P. wallichiana, and often described as a variety of that species (Bachman et al. 2007). For discussion of systematics relative to other species in subsection Strobus, see Phylogeny of East Asian white pines.

Description

Trees to 25+ m tall with an open crown of spreading, drooping, sinuous branches. Bark unknown. Branchlets glandular, pubescent,with a whitish bloom; in second year developing a thin, pale gray-green bark. Needles shed in second year, 5 per fascicle, very slender, curved, pendulous, 15-24 cm long; triangular in cross section, stomata only on the 2 abaxial surfaces, each with 4-7 stomatal lines, resin canals 3(-4), 2 adaxial marginal or submarginal, 1(-2) abaxial marginal or submarginal, asymmetrically placed. Seed cones elongate-cylindric, 12-20 × 3-4 cm (5-7 cm wide when open), on a (1-) 4.5-6 cm peduncle. Seed scales elongate, thinly woody, with cuneate base; apophyses rhombic, 1-1.5 × 1.5-2.5 cm, keeled, apex subacute. Seeds brown, obovoid, compressed, 6-8 × 4-5 mm; wing persistent, ca. 2 × 0.7-1 cm (Wu and Raven 1999).

"P. bhutanica, however, is easily distinguished by its thin, pruinose, dark brown, finely glandular branchlets and vertically drooping, finer needles with long, golden sheaths while P. wallichiana has thick, succulent, grayish-green, evenly wide branchlets and partially outspreading needles with shorter, grayish sheaths" (Debreczy and Racz 2009).

Distribution and Ecology

Bhutan; China: Yunnan; India: Arunachal Pradesh (Farjon 1998). Its distribution is still not well known; data from labeled herbarium specimens indicate that it occurs at elevations of 729 to 2,750 m in mixed pine forest, mixed oak-pine forest, mixed broadleaved forest, and secondary forests of these types, including thinned (managed?) forest (Bachman et al. 2007). Hardy to Zone 9 (cold hardiness limit between -6.6°C and -1.1°C) (Bannister and Neuner 2001).

"It is also thought to occur more widely eastwards, but botanical collecting has been virtually absent in this region since this species was first described in 1980. It is reported to be harvested as part of a mixed timber resource, but there is no evidence of decline and new localities have been found. New collections have recently been made in China (Yunnan, Gaoligong Mts.) and an assessment of the species in this area is required" (Bachman et al. 2007).

Remarkable Specimens

In April 2022, a 76.8 m tall individual was found near Gelin in Medog Xian, Tibet. The tree was measured by Guo Qinghua and associated researchers from Peking University using LIDAR, and is one of 6 P. bhutanica over 70 m tall found in the area (Xinhua 2022). That makes this the second-tallest white pine in the world, excepting only a dozen or so Pinus lambertiana in Oregon and California.

Ethnobotany

Bachman et al. (2007) report that it has been harvested for timber.

Observations

Reported to occur in the Khaling and Bumdeling Wildlife Sanctuaries in Bhutan (Bachman et al. 2007).

Remarks

Citations

Bachman, S., A. Farjon, M. Gardner, P. Thomas, D. Luscombe, and C. Reynolds. 2007. Pinus bhutanica. In: 2008 IUCN Red List of Threatened Species. www.iucnredlist.org, accessed 2009.04.10.

Z. Debreczy and I. Rácz, 2011. Conifers Around the World. Vols. 1-2. Budapest: DendroPress Ltd.

Grierson, A.J.C., D.G. Long, and C.N. Page. 1980. Notes Roy. Bot. Gard. Edinburgh 38:299.

Xinhua. 2022.05.10. Chinese mainland registers tallest tree in Tibet. https://english.www.gov.cn/news/photos/202205/10/content_WS6279c23ec6d02e533532a7d6.html, accessed 2022.07.26.

See also