Amentotaxus yunnanensis

H.L. Li (1952)

Common names

Dẻ tùng sọc nâu rộng, Sam bông, Thộng tre vân nam [Vietnamese].

Taxonomic notes

Syn.: Amentotaxus hatuyenensis T.H.Nguyên. Nguyên's species was only known from a few locations in Viet Nam and differed from A. yunnanensis only in the color of the stomatal bands. Molecular studies (Phan et al. 2014, Gao et al. 2016) subsequently showed that collections of A. hatuyenensis fall entirely within the range of variation seen in A. yunnanensis.

There is one named hybrid: Amentotaxus × hybridia L.M.Gao & G.L.Zhang (2023), reported from Hekou County in Yunnan, is the hybrid of A. yunnanensis and A. hekouensis; see Gao et al. (2023) for photos and a line drawing.

Description

Tree to 20 m tall and 25 cm dbh, with a wide, ovate crown. "Twigs opposite, smooth or slightly lined, green or glaucous, turning yellow, yellowish or yellow-grey after 2-3 years. Leaves subopposite, arranged into 2 rows, 3.5-10(15) cm long and 8-15 mm wide, narrowly lanceolate or linear, straight or curved on upper part, obtuse or pointed with subrounded or broadly cuneate base. Margin slightly revolute. Midrib evident above, flat beneath, two bands of stomata on both surfaces, usually white or grey, 2-4 mm wide. In leaf-buds, band of stomata often narrower. Female cone spike-like, with 4-6 spikes at the branch-tips, 10-15 cm long. Each stamen bears 4-8 anthers (usually 6-7). Fruit often solitary on the annual branches, downcurved, ovate, 2.2-2.8 cm long and 1.4 cm wide. Pericarp violet-red when mature, slightly covered with white powder. Stalk stout, 1.5 cm long, lower part flat, upper part quadrangular" (FIPI 1996).

"Amentotaxus × hybridia L.M. Gao has linear or linear-lanceolate leaves 6–13 cm × 1.0–1.5 cm, white stomatal bands with 34–40 rows on abaxial side, 2.5–3.5 mm, slightly wider than leaf margins; 3–6 seeds borne at the base of the branchlet, peduncle 1.3–1.6 cm long with 3–4 rows of persistent basal bracts" (Gao et al. 2023).

Distribution and Ecology

China: Yunnan and Viet Nam. In Viet Nam found in primary forest of Ha Giang and Lao Kai provinces, at elevations of 700-1500 m. Habitat is mainly steep limestone karst mountains with frequent fog and annual precipitation of about 1,800 mm, and temperatures of 15-18°C. Mesic tree, shade-tolerant when young. Usually mixed with other conifers such as Cephalotaxus mannii, Chamaecyparis hodginsii, Nageia fleuryi, Pinus fenzeliana, Podocarpus neriifolius, P. pilgeri, Tsuga chinensis and Xanthocyparis vietnamensis, as well as with various angiosperm trees and a rich epiphytic flora (FIPI 1996, Hiep et al. 2004, Farjon 2010). Hardy to Zone 9 (cold hardiness limit between -6.6°C and -1.1°C) (Bannister and Neuner 2001).

Distribution data from GBIF (2022). A. yunnanensis is green.

The IUCN (2017) assessed A. yunnanensis as "vulnerable" based on (1) an ongoing but gradual population decline of 30-50% in the past 75 years, and (2) a relatively wide area of occurrence in Viet Nam, considerably greater than in Yunnan, where it is still assessed as "Endangered".

Remarkable Specimens

No data as of 2023.02.23.

Ethnobotany

Wood used for furniture. Seeds contain oil. Can be planted as a shade or decorative tree (FIPI 1996).

Observations

In Viet Nam, where it is endangered, it is protected in Hoang Lien Son Nature Reserve and reportedly occurs in the Dong Van Karst Plateau Geo-Park.

Remarks

The epithet refers to China: Yunnan.

Citations

Gao L.-M., Y. Li, L. K. Phan, L. J. Yan, P. Thomas, K. P. Long, M. Möller, and D. Z. Li. 2016. DNA barcoding of East Asian Amentotaxus (Taxaceae): Potential new species and implications for conservation. Journal of Systematics and Evolution 55(1):16–24.

Gao, L.-M., Zhang, G.-L., Mo, Z.-Q., and Thomas, P. 2023. Amentotaxus × hybridia (Taxaceae), a new natural Amentotaxus hybrid from southeast Yunnan province, China. PhytoKeys 226:101–108. https://doi.org/10.3897/phytokeys.226.103005.

Hiep, N.T. 1996. Flore du Cambodge, Laos et Viet Nam 28:126.

Li Hui-Lin. 1952. A taxonomic review of the genus Amentotaxus. Journal of the Arnold Arboretum 33:197. Available: Biodiversity Heritage Library, accessed 2021.12.19.

Phan K. L., K. L. Phan, T. M. L. Le, and G. S. Nguyen. 2014. Molecular characterization of Amentotaxus hatuyenensis N.T. Hiep (Taxaceae) based on ITS1 partial sequence. VNU Journal of Science: Natural Sciences and Technology 30(3S):46–52.

See also

The species account at Threatened Conifers of the World.

Nguyen Tien Hiep, Phan Ke Loc, Nguyen Duc To Luu, Philip Ian Thomas, Aljos Farjon, Leonid Averyanov, and Jacinto Regalado Jr. 2004. Vietnam Conifers: Conservation Status Review 2004. Hanoi: Fauna & Flora International, Vietnam Programme.

Luu, Nguyen Duc To and Philip Ian Thomas. 2004. Cay La Kim Vietnam / Conifers of Vietnam. Darwin Initiative. ISBN 1 872291 64 3. Available: http://www.ceh.ac.uk/sections/bm/conifer_manual.html, accessed 2006.03.08, now defunct. The authors provide a description, range map, conservation status, drawings and photos, and a wealth of additional information.