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Over at https://www.facebook.com/groups/planetconifer/permalink/7042971009066159/ Jean Hoch discusses the true nature of the species and the confusion around it.
There is obviously a lot of confusion about the name of the tallest tree in Asia discovered in May 2023. According to various sources, it is about Tibet cypress, Cupressus gigantea, Cupressus torulosa, and sometimes also Buthan cypress.
The reference to the Bhutan cypress refers to the previous record holder of 2022, (76.8 m) of a tree found in the Medog district of Tibet and it is a Pinus buthanica.
In Chinese, the vernacular name for Cupressus gigantea is giant cypress (巨柏 Jù bǎi). This species is found further west in the Yarlung Zangbo Valley between approximately 29°02'43.0"N 93°01'47.0"E and approximately 29°27'16.0"N 94°31'31.0"E.
The 102 m record tree is located at the confluence of the Parlung Zangbo and the Yi'ong Zangbo, near the commune of Tongmai in the district of Bôme, 30°06'03.9"N 95°04'47.3" E. In this place the climate is much more humid and it is another species, Cupressus austrotibetica.
Before recognizing C. gigantea, A. Farjon (Kew) had long considered all Tibetan cypresses to be C. torulosa. These are the “C. torulosa” of the Bôme County which the Chinese call Tibet cypress, in fact, they call it Xizang cypress (西藏柏木 Xīzàng bǎimù). Tibet being the translation of Xizang. Since Farjon it has turned out that genetically C. gigantea and C. austrotibetica are indeed species in their own right. There is however a big problem for the Chinese, although C. austrotibetica is a valid and accepted species name, its scientific name contains the word “Tibet” and I don't know why this blocks them. Rather than accepting this scientific name, they continue to call these cypresses C. torulosa.
But, in reading a Chinese article on the tallest tree in Asia, another problem seems to be looming. Indeed, in the Cupressus Conservation Project Bulletin 10(2): (2021) we reported the presence of a second species located 3 km east of Tongmai, Cupressus rushforthii, which the Chinese now call Tongmai cypress (通麦 柏木 Tōngmài bǎimù). There is therefore a risk of confusion with Cupressus tongmaiensis which is a synonym of C. austrotibetica.
In summary :
Cupressus tongmaiensis = Cupressus austrotibetica
Tongmai cypress (Tōngmài bǎimù) = Cupressus rushforthii
Tibet cypress (Xīzàng bǎimù) = Cupressus austrotibetica (« the C. torulosa » of the Palung Zangbo and the Yi’ong Zangbo valley)
Giant cypress (Jù bǎi) = Cupressus gigantea
Asia's tallest tree (102 m) = Cupressus austrotibetica
