Juniperus tsukusiensis

Masamune (1930a)

Common names

清水圆柏 qing shui yuan bai (Fu et al. 1999).

Taxonomic notes

Type: Japan, Kyushu, Yakushima; G. Masamune s.n., syntype TI. There are two varieties, Juniperus tsukusiensis var. tsukusiensis, endemic to Japan; and Juniperus tsukusiensis var. taiwanensis (R.P.Adams & C.F.Hsieh) R.P.Adams (2011), endemic to Taiwan. The type of the latter variety is Taiwan, Mt. Chingshui, elev. 2200 m; Lu Shengyou 14498, holotype TAIF.

See POWO for full synonymy of species and varieties. Long accepted as a variety of J. chinensis, this taxon has now been accepted at species rank on the basis of molecular evidence (Adams et al. 2011), which also identifies certain differences between the Japan and Taiwan varieties. However, it remains sister to J. chinensis within a highly diverse clade of Section Sabina (Adams and Schwarzbach 2013, Farhat et al. 2019). Given the habitat and range differences relative to J. chinensis, this could also be treated as Juniperus chinensis subsp. tsukusiensis (Masam.) Silba 2006.

Description

Dioecious evergreen procumbent shrubs with erect branches. Bark brown, exfoliating in plates and strips. Terminal twigs ascending. Leaves dimorphic; needle-like leaves usually densely arranged in whorls of 3, 6 × 1 mm, apex acute, adaxially concave, abaxially carinate; scale leaves 1.5 × 1 mm. Pollen cones not described. Seed cones globose, about 5 mm diameter, bluish-black. Seeds 3, erect, trigonal-elliptic, 3 mm long, 2 mm wide (Iwatsuki et al. 1995, Fu et al. 1999, Adams 2014).

Neither Adams (2011), nor any other source I can located, identifies any morphological or ecological differences between the varieties. They are distinguished only by distribution, essential oil composition, and genetic markers.

Distribution and Ecology

The varieties are disjunct. Var. tsukusiensis is endemic to subtropical Yakushima Island, off the south coast of Kyushu, Japan. It occurs at elevations from 500 m to the summits of the island (Masamune 1934), but otherwise its habitat and ecology seem to have gone unstudied. Var. taiwanensis is endemic to elevations from 2200 m to the summit of Chingshuishan, in Taroko National Park, Hualien Xian. It grows on limestone (Li 1975, Adams 2014).

Although the IUCN assigns this species a conservation status of "Data Deficient", it appears to warrant a status of "Endangered" based simply upon its tiny area of occurrence. Although the known populations occur within protected areas, that statutory protection does not protect them from natural disasters or adverse changes in governance.

Remarkable Specimens

No data as of 2023.02.21.

Ethnobotany

No data as of 2023.02.21.

Observations

In Japan, Yakushima Island is probably the most amazing place in the whole country to see conifers. J. tsukusiensis can be found near the summit of Mt. Miyanoura, the island's high point, but the island also hosts the largest and oldest known specimens of Cryptomeria japonica, and is also home to exceptional occurrences of Chamaecyparis obtusa, Pinus amamiana, Pinus thunbergii, Abies firma, Tsuga sieboldii, Taxus cuspidata, and Torreya nucifera (Businsky 2017). The island is a very popular ecotourism destination, so it's easy to visit. It's also the wettest place in Japan, so bring your rain gear.

In Taiwan, the high country of Taroko National Park looks like a good place to see it.

Remarks

Masamune (1930a) does not give the origin of the epithet "tsukusiensis", but it likely refers to Tsukushi, which is an old name for Kyushu, Japan's southernmost major island. "Tsukusiensis" was probably a spelling error by Masamune, since the epithet "tsukushiensis" has been applied to a number of other southern Japanese taxa.

Citations

Adams, Robert P., Chang-Fu Hsieh, Jin Murata, and Andrea E. Schwarzbach. 2011. Systematics of Juniperus chinensis and J. tsukusiensis from Japan and Taiwan: DNA sequencing and terpenoids. Phytologia 93:118–131.

Adams, Robert P., and Andrea E. Schwarzbach. 2013. Phylogeny of Juniperus using nrDNA and four cpDNA regions. Phytologia 95:179–87.

Businský, Roman. 2017. Japonsko, prefektura Kagošima, ostrov Jakušima. https://botany.cz/cs/jakusima/, accessed 2025.01.04. This page also has some excellent photographs of the Yakushima conifers.

Farhat, P., O. Hidalgo, T. Robert, S. Siljak-Yakovlev, I. J. Leitch, R. P. Adams, and M. Bou Dagher-Kharrat. 2019. Polyploidy in the conifer genus Juniperus: an unexpectedly high rate. Frontiers in Plant Science 10, doi: 10.3389/fpls.2019.00676.

Herbarium of the Research Center For Biodiversity, Academia Sinica, Taipei [HAST]. 1999. Database output at http://www2.sinica.edu.tw:8080/hast/eindex.html, accessed 1999.03.15, now defunct.

Masamune, G. 1930a. A contribution to the phytogeography of the island of Yakushima. Shokubutsugaku zasshi (Botanical Magazine Tokyo) 44:43-52 (p. 50). Available: doi.org/10.15281/jplantres1887.44.43.

Masamune, G. 1930b. J. Soc. Trop. Agric. Formosa 2: 152.

Masamune, G. 1934. Floristic and geobotanical studies on the island of Yakushima, Province Osumi. Memoirs of the Faculty of Science and Agriculture, Taihoku Imperial University, Vol. XI. BOTANY No. 4. Available Botanical Survey of India, accessed 2025.01.03.

See also

Farjon (2005) provides a detailed account, with illustrations.

Huang 1994 (the Flora of Taiwan).