クロマツ, 黒松, kuro-matsu [Japanese]; Japanese black pine.
Syn: P. thunbergiana Franco; P. thunbergii Lamb., nom. illeg.; P. massoniana sensu Sieb. & Zucc., non Lamb. It belongs to the large subsection Pinus, within which it seems to be most closely related to P. hwangshanensis and P. nigra (Hsia 1936, Farjon 1984). Recent sequencing of its chloroplast genome (Wakasugi et al. 1994) provides hope that its phylogeny will soon be well understood, but 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, providing a plausible linkage to western Asian populations of P. nigra (Millar 1998).
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.).
Japan: Honshu, Shikoku and Kyushu; S Korea (Ohwi 1965). It 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).
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).
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.
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).
The lower two illustrations at left 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.
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. www.nara.accu.or.jp/elearning/2004/architectural.pdf, accessed 2009.08.24.
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.
This page co-edited with M.P. Frankis.
Last Modified 2012-11-28