The diversity of the flora of Vietnam 17. Anodendron howii Tsiang (Apocynaceae), new species occurrence for the flora

SUMMARY

Acknowledgements. Field explorations and taxonomic studies presented in this paper have been funded by an International Cooperative Biodiversity Groups (ICBG), Grant No. 1-UO1-TW01015-01, through funds from the National Institutes of Health (NIH) and the National Science Foundation (NSF) of the United States, and the Foreign Agricultural Service of the United States Department of Agriculture (USDA). Permit for the collection and export of plant specimens for study was granted by the Ministry of Agriculture and Rural Development, Hanoi, and by the Cuc Phuong National Park (Letter Ref. No. 3551/BNN/KHCN, dated September 16, 1998). Thanks are expressed to Drs W.D. Stevens and D.J. Middleton in assisting with the taxonomic identification.

Anodendron howii Tsiang, a new record of its occurrence for the flora of Vietnam, was known previously as a local endemic to Guangxi and Hainan provinces of China. This is the fourth species of the genus Anodendron A. DC. in Vietnam, the other three being A. laeve (Champ. ex Benth.) Maxim. ex Franch. & Sav., A. paniculatum A. DC. Pham Hoang Ho, and A. nervosum Kerr. The plant is a vine of about 8 m long, with the young branchlets, petioles and veins puberulent beneath; the leaf blade with 14-16 prominent pairs of lateral veins; the axillary cymes paniculate, 3.5-5.5 cm long, shorter than the subtending leaves; flowers with pedicels 2-2.5 mm long, corolla tube 1.8 by 0.7 mm, corolla lobes in bud strongly twisted to the right, ca. 3.2 by 0.9 mm, glabrous outside and slightly pubescent inside of the tube, stamens inserted at 0.4 mm from the corolla base, anthers 0.7 by 0.3 mm, disk 5-crenate, 0.4-0.5 mm long, ovary 0.4-0.5 mm long, style and pistil head 0.9 mm long. According to the description provided by P.T. Li et al. (1995) and by D.J. Middleton (1996), specimens in China have fruits of 10.9-11.2 cm by 1.4-1.6 cm; seed grain 12-15 mm by 5.4-5.7 mm; beak 6-7.8 mm; coma 3.9-4.1 cm long. Specimen examined: Nguyen Manh Cuong & Mai Van Xinh NMC 843, very rare, mainly at the edge of primary, closed, evergreen tropical seasonal broad-leaved lowland forests, in valleys and foothills of limestone mountains, in a region with tropical monsoon climate, namely, cold and dry winter and rainy summer, an average annual temperature of about 23⁰C, with 3 cold months, an annual monthly temperature of less than 18⁰C (December, January and Febuary), an annual precipitation of 1,700-1,900 mm, and with 4-5 dry months (from December to March and April). Flowers bloom in June; fruits not seen.

Phan Ke Loc
University of Sciences, VNU & Institute of Ecology and Biological Resources
Nguyen Tien Hiep
Institute of Ecology and Biological Resources
D.D. Soejarto
University of Illinois at Chicago & Field Museum, Chicago
Nguyen Manh Cuong
Cuc Phuong National Park