Tsaiodendron, a new genus of Euphorbiaceae, found in Yuanjiang dry-hot valley

During their recent floristic explorations of the Yuanjiang valley collected an unusual species. After carrying out analysis, the researchers confirmed it as a new species and named it as Tsaiodendron dioicum.

Euphorbiaceae is one of the largest family of angiosperms, with 218 genera and 6462 species currently recognized. Mr. Yunhong TAN  researchers from Xishuangbanna Tropical Botanical Garden (XTBG) ,as well as the leader of Plant Diversity and Conservation Research Group of CAS-SEABRI, together with Kunming Institute of Botany (KIB),  during their recent floristic explorations of the Yuanjiang valley collected an unusual species.

The plant was easily identified as a member of Euphorbiaceae based on the three-lobed capsule and unisexual flowers. After carrying out molecular phylogenetic study and molecular divergence dating analysis, the researchers confirmed it as a new species and named it as Tsaiodendron dioicum.

The new taxon differs from the rest of Epiprineae in being deciduous shrubs in situ. It is dioecious. The inflorescences terminal are on leafy spur (short lateral) shoots and staminate inflorescences sessile, one- or several-flowered. The flowers emerge sequentially and pistillate inflorescences are one-flowered. The flowers are with disc glands.

The genus is named in honor of the late Prof. Cai Xitao (Tsai Hse-Tao, 1911–1981), founder of XTBG, and who devoted all his life to the study of Chinese plants.

The new genus is monotypic. It is endemic to China, and only found in Yuanjiang dry-hot valley, Yunnan.  

Only one population and about 500 individuals of Tsaiodendron dioicum were found in Yuanjiang dry-hot valley. It is threatened due toincreasing habitat loss and human activities.

The study entitled “Molecular phylogenetic analyses of Euphorbiaceae tribe Epiprineae, with the description of a new genus, Tsaiodendron gen. nov., from south-western China” has been published online in Botanical Journal of the Linnean Society.

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Tsaiodendron dioicum Y.H.Tan, Z.Zhou & B.J.Gu gen. nov., sp. nov. (A) habit; (B) twig, showing lower surface of leaves; (C) leaf blade; (D) male flower; (E–G) female flower; (H–I) fruit. Photographs by Yun-Hong Tan and Bo-Jian Gu.

Contact

TAN Yunhong Principal Investigator

Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China

E-mail: tyh@xtbg.org.cn