An unusual conifer found in a remote area of northern Vietnam has been identified as a genus and species previously unknown to science.
The limestone ridges where the tree grows are among the most botanically rich areas in Vietnam and certainly harbor many other undescribed species, but they are outside the country's protected reserves, said Daniel Harder, director of the Arboretum at the University of California, Santa Cruz, and a codiscoverer of the new species.
Harder spent several years in Vietnam as the founding director of a botanical conservation program for the Missouri Botanical Garden. During that time, he and his collaborators discovered more than 100 new species of plants. But the conifer now known as the golden Vietnamese cypress is by far the most remarkable of those discoveries, he said.
"For us to find a previously undescribed large tree like this indicates that there is probably a lot more to be discovered there," Harder said. "It's comparable to the recent discoveries of previously unknown large mammals in Southeast Asia, like the giant muntjac and the saola, a type of ox."
Other scientists involved in the conifer discovery included Vietnamese botanists Nguyen Tien Hiep and Phan Ke Loc, Russian botanist Leonid Averyanov, and Philip Cribb from the Royal Botanic Gardens, Kew, in the United Kingdom. They found the trees clinging to steep limestone ridges in a mountainous area known as Bat Dai Son near the Chinese border.
The scientists knew they had found something interesting and sent specimens of the plant to one of the world's leading conifer specialists, Aljos Farjon at Kew. Farjon was initially skeptical of the group's reported find, but when he received the specimens he was ecstatic, Harder said.
"He's spent 25 years studying conifers and had never had an opportunity to describe a new species before," Harder said.
Farjon classified the tree as a new genus within the cypress family (Cupressaceae), and he and the other botanists have named it Xanthocyparis vietnamensis, the golden Vietnamese cypress. Its closest relative is the yellow spruce of the U.S. Pacific Northwest, also known as the Nootka cypress.
Previously classified as Chamaecyparis nootkatensis, the yellow spruce is now classified as the second species in the new genus Xanthocyparis.
Harder noted that the name change from Chamaecyparis nootkatensis to Xanthocyparis nootkatensis is not likely to sit well with horticulturists and foresters because the considerable bibliographic information on this important timber tree is linked to the old name.
"They dislike it when botanists change the names of familiar species, but these two trees are clearly the closest relatives of each other," he said.
A formal description of the new species is expected to be published in the next issue of the botanical journal Novon. A description of the tree's natural habitat and associated species will appear soon in another botanical journal.
A distinctive and unusual feature of the new species is that it bears two different types of foliage on mature trees: needles and scale leaves. It produces fine, yellowish-brown, hard, fragrant timber that is highly prized by the local people.
Logging has reduced the number of larger trees, but some very large and stately specimens still grow on the steep, rocky slopes of isolated mountain peaks, Harder said. The mountaintop ridges in Bat Dai Son hold remnants of a forest that was once much more widespread, he added.
"This tree was already rare and endangered when it was discovered, which lends urgency to putting in place some protections," Harder said. "These limestone mountains might actually harbor other valuable species, and it's all part of the national heritage of Vietnam."
Based on the work of Harder's botanical conservation program within Bat Dai Son, the provincial government of Ha Giang Province has established the Bat Dai Son protected area. Provincial protection is the first step toward national and international protection, Harder noted.
In addition to the cypress, the collaborative team of botanists exploring the area has found about two dozen new orchid species, a variety of interesting new shrubs, and numerous herbs and bulbs, including a half-dozen new species in the Jack-in-the-pulpit family (Araceae).
"We have sent specimens to specialists around the world, and that has really stimulated a lot of interest in the flora of Vietnam," Harder said.
Harder has made plant conservation a central programmatic theme for the UCSC Arboretum since taking the helm as director in October 2001. He noted that the Arboretum already has a significant collection of conifers from around the world, in addition to its renowned collections of plants from Australia, New Zealand, and South Africa. But conservation involves much more than growing rare plants in the gardens, Harder said.
"We want to be active partners in conservation efforts to protect not only the plants themselves but also the habitats in which they grow," he said. "I also see education as an important part of conservation, and we have a role in explaining for the public the significance of rare and threatened plants. The Arboretum has a lot of work to do in these areas." - By Tim Stephens
Foliage and cones of the golden Vietnamese cypress, X. vietnamensis. Credit: D. K. Harder
[Contact: Daniel Harder, Tim Stephens]