Cupressus rushforthii
As of late 2024, none have yet been attributed.
Type: Tree cultivated at Ness Botanic Garden from KR6015 clone B. The material was collected in China, Xizang, Bomê County, Parlung Tsangpo, close to Tangdui (30.10199°N, 95.10428°E, elevation 2100 m), K.Rushforth KR6015, 1999.10.02. Rushforth noted that the specimen was collected from “one of two trees growing at the edge of a steep cliff at the edge of a small side stream on the right bank of the Parlung Tsangpo, but in some shade from the mountains to the south, on the left bank" (Maerki and Hoch 2021). No synonyms.
An RAPD analysis placed this specimen sister to C. austrotibetica in a clade with C. majestica and C. duclouxiana (Rushforth et al. 2003). This has been accepted by POWO treats as a valid species, however Li et al. (2024) reduce it to synonymy with C. austrotibetica, citing the same RAPD analysis and questioning whether there are any obvious morphological differences between the two species (they did not contact Maerki or Hoch, who could have addressed the question). In fact, Maerki and Hoch (2021) provide descriptions of both taxa, and those descriptions identify no differences. Moreover, this specimen has only been seen in habitat once, in the form of two roadside saplings, and Maerki and Hoch (2021) report only 3 cultivated specimens, all taken from that one collection over 25 years ago.
Monoecious evergreen trees with pyramidal crowns. Bark first red-brown, exfoliating in plates, later turning gray and exfoliating in strips. Foliar units are flattened sprays. Leaves acicular, appressed to twig, often with an inactive resin gland on facial leaves. Seed cones globose, dark green before maturity with small light green mucros, turning light brown to dark brown and opening at maturity, averaging 12-16 × 12-15 mm with length/width ratio averaging 0.96, and (8-)10(-12) scales. Seeds 3-4 × 2-3 mm with narrow wings and a marked tip at the extremity opposite the hilum. Cotyledons two. Seedlings to 25 cm tall after one growing season, still with glaucous juvenile foliage, branches spreading regularly and almost horizontally (Maerki and Hoch 2021).
This brief description does not indicate any differences relative to C. austrotibetica.
The one collection was from the banks of the Tsangpo near Tangdui, Tibet (China: Xizang), elevation 2100 m. Maerki and Hoch (2021) suggest that the saplings observed by Rushforth grew from seed transported from much higher on the mountain, and "It will be necessary to explore the mountain above Tangdui in search of the parent trees to be able to assess this new species’ population." There are other possible explanations for the saplings; for instance unique roadside trees can often be traced to human activity. The conservation status of the species is unknown.
One source alleges that the tallest tree in China is not C. austrotibetica, but C. rushforthii (Guo 2023).
No uses have been reported.
Besides the type collection, cited above, cultivated trees cloned from the type are at Royal Botanical Garden Kew and Ness Botanical Garden, both in the U.K.
The epithet honors Keith Rushforth, who performed the first and only (as of 2024) collection of this species in habitat. Besides, he's one of the most eminent living taxonomists, having published extensively on conifers and other plants in the scientific and popular press; here's a short bibliography.
Guo, Qinghua. 2023. The thickest, tallest, and oldest C. rushforthii (Cupressus rushforthii). Monumental Trees. https://www.monumentaltrees.com/en//trees/cupressusrushforthii/records/, accessed 2024.12.09.
Li, Jialiang, Dayu Wu, and Kangshan Mao. 2024. Taxonomy and diversity of the genus Cupressus: current status and recommendations. Journal of Nanjing Forestry University 48(3):36–45.
Maerki, Didier, and Jean Hoch. 2021. Cupressus rushforthii, a new cypress species in Xizang, China. Bulletin of the Cupressus Conservation Project 10(2):57.
Rushforth, Keith D., Robert P. Adams, M. Zhong, X.-qiang Ma, Ram Naresh Pandey, et al. 2003. Variation among Cupressus species from the eastern hemisphere based on random amplified polymorphic DNAs (RAPDs). Biochemical Systematics and Ecology 31(1):17–24.
Last Modified 2024-12-13
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