Pinus thunbergii

Parlatore 1867

Common names

クロマツ, 黒松, kuro-matsu [Japanese]; Japanese black pine. Pinus × densithunbergii names include Aiguro-matsu and Akakuro-matsu [Japanese].

Taxonomic notes

Synonymy: P. thunbergiana Franco 1949; P. thunbergii Lamb., nom. illeg.; P. massoniana sensu Sieb. & Zucc., non Lamb.

Pinus × densithunbergii Uyeki 1953 is the natural hybrid between P. densiflora and P. thunbergii. It was first described as a species, P. densi-thunburgii Uyeki 1926.

P. thunbergii belongs to the large subsection Pinus, within which molecular analysis groups it with 7 of the 8 other temperate east Asian species in the subsection (Gernandt et al. 2005).

Description

Trees to 40 m tall, with trunk often divided in the wide, dense, dome-shaped or flattened crown. Bark dark gray or purple-gray, scaly, longitudinally fissured. Branches light brown with many bracts, thereafter becoming glabrous, often ridged. Young shoots covered with a dense whitish tomentum that is highly distinctive among pines. Winter buds white, slightly resinous, 1.5-2 cm long, ovoid, pointed. Needles 2 per fascicle, 7-12 cm long, 0.7-1.2 mm wide, acute, dark green, scabrous with minute marginal teeth, often twisted, persisting 3-4 years. Cones short-pedunculate, conic-ovoid, 4-7 cm long, 3.5-6.5 cm wide, buff to brown-gray, opening in late winter. May be single, paired or (in selected cultivars where the pollen cones are replaced by seed cones) very numerous (20 or more) to a shoot. Cone scales numerous, cuneate, the apophysis flattened and transversely rhomboidal, with a short-mucronate umbo, pale brown to buff; the scale stem dark purple-brown to blackish above, pale brown below; opening to 60-80° wide (c.f. P. hwangshanensis), 18-28 mm long, 8-12 mm wide. Seeds dark brown to black, 6 mm, with an articulate 12-16 mm wing (Ohwi 1965, Farjon 1984, M.P. Frankis pers. obs.).

Similar species: Pinus densiflora have bark that, on mature trees, forms large plates (not longitudinally fissured); the umbo of the cone bears a small prickle (typically deciduous).

P. × densithunbergii has characters intermediate between the parent species. The leaves have a combination of marginal and medial resin ducts, whereas resin ducts are marginal in P. thunbergii and medial in P. densiflora (Farjon 2010).

Distribution and Ecology

Japan: Honshu, Shikoku and Kyushu; S Korea (Ohwi 1965). This is also the distribution of P. × densithunbergii. P. thunbergii is the dominant pine from the coast to about 1000 m elevation (Richardson and Rundel 1998).

Hardy to Zone 6 (cold hardiness limit between -23.2°C and -17.8°C) (Bannister and Neuner 2001).

Since the early 20th century, native populations of P. thunbergii have been decimated and may ultimately be eliminated by pine wilt disease, caused by the nematode Busaphelenchus xylophilus. The disease is native to North America, where it has no apparent ill effect on native pines, but the Asian pines P. luchuensis and P. thunbergii apparently have no resistance to it. It is introduced to needles when they are grazed by longhorn beetles (Coleoptera: Cerambycidae) and effectively defoliates the trees. As the trees die and are invaded by blue stain fungi, the nematodes begin to feed on the fungi. Longhorn beetles lay eggs in the bark of the dying trees, providing the nematodes with their transport vector. The nematode is also deadly to P. sylvestris, the world's most widespread pine species, and there is great concern in Europe that the nematode might one day reach that continent (Harrington and Wingfield 1998).

Remarkable Specimens

Ethnobotany

Historically, this has been one of the most important species used in Japanese architecture. The principal structural woods in most surviving structures of the Muromachi period (14th to 16th Centuries) and the Edo period (1603-1867) are Pinus densiflora and P. thunbergii, although surviving structures also contain a great deal of Chamaecyparis obtusa (Takao 2004).

Widely used as an ornamental, and requisite in Japanese gardens, where it provides structural and symbolic counterpoint to the red pine P. densiflora.

Air pollution has caused needle chlorosis, reduced needle retention and a decline in community diversity in forests near Korean cities (Richardson and Rundel 1998).

Observations

It is reportedly very common in lowlands within its range. Thanks to its wide popularity as an ornamental, it can be seen through much of the temperate zone.

Remarks

The epithet remembers Carl Peter Thunberg (1743-1828), who published an early flora of Japan (Farjon 2010).

Current understanding suggests that along with P. densiflora and P. yunnanensis, it may have found a warm-temperate refugium in central Asia during the mid-Tertiary (Millar 1998).

The lower two illustrations at right are from the first installment of Siebold and Zuccarini's Flora Japonica, issued in 1835. Philipp Franz von Siebold visited Japan from 1823-1829 as a doctor and scientist in the employ of the Dutch East India Company. During this time he collected thousands of plant and animal specimens, many of new species that were later named for him. Among the conifers, he is commemorated by Tsuga sieboldii.

Citations

Farjon, Aljos. 2010. A Handbook of the World's Conifers. Leiden, Netherlands: Brill Academic Publishers.

Gernandt, D. S., G. Geada López, S. O. Garcia and A. Liston. 2005. Phylogeny and classification of Pinus. Taxon 54(1):29-42.

Harrington and Wingfield in Richardson 1998.

Hsia, W. Y. 1936. Flowering plants of Hwangshan. Contrib. Inst. Bot. Nat. Acad. Peiping 4: 155-156.

Millar in Richardson 1998.

Parlatore, F. 1867. Coniferae (Ordo CXCIX). Pp. 361-521 in A. P. de Candolle and Alph. de Candolle (eds.), Prodromus systematis naturalis regni vegetabilis, vol. 16, part 2. Paris (p. 388).

Takao, Itoh. 2004. Architectural development of the Japanese house and wood species used for construction. http://www.nara.accu.or.jp/elearning/2004/architectural.pdf, accessed 2009.08.24, now defunct.

Uyeki, Homiki. 1953. Scientific Reports of the Matsuyama Agricutural College 10:6.

This page co-edited with M.P. Frankis.

See also

Elwes and Henry 1906-1913 at the Biodiversity Heritage Library. This series of volumes, privately printed, provides some of the most engaging descriptions of conifers ever published. Although they only treat species cultivated in the U.K. and Ireland, and the taxonomy is a bit dated, still these accounts are thorough, treating such topics as species description, range, varieties, exceptionally old or tall specimens, remarkable trees, and cultivation. Despite being over a century old, they are generally accurate, and are illustrated with some remarkable photographs and lithographs.

Wakasugi T., Tsudzuki J., Ito S., Nakashima K., Tsudzuki T. and Sugiura M. 1994. Loss of all ndh genes as determined by sequencing the entire chloroplast genome of the black pine Pinus thunbergii. Proceedings of the National Academy of Sciences, USA 91: 9794-9798.