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Cupressus vietnamensis

Cupressus vietnamensis
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Product Information
Specification

Scientific name: Cupressus vietnamensis  (Farjon & T.H.Nguyên) Silba  2005

Synonyms: Callitropsis vietnamensis (Farjon & T.H.Nguyên) D.P.Little, Xanthocyparis vietnamensis Farjon & T.H.Nguyên

Common names: Golden Vietnamese cypress, Vietnamese yellow cedar (English), Bách vàng (Vietnamese)

 

Description

Tree to 15 m tall, with trunk to 0.5 m in diameter. Bark reddish brown to purplish when fresh, weathering brown to grayish brown, becoming shallowly furrowed and peeling in long, narrow strips. Crown conical at first, becoming dome-shaped and irregular with age, with long, slender, upwardly angled to horizontal branches. Branches with juvenile and transitional foliage present on adult trees. Juvenile leaves 1.5-2 cm long, sticking straight out from the branchlets in alternating whorls of four separated by 4-5 mm. Branchlets bearing adult foliage flattened, 0.8-2(-3) mm wide, mostly arranged in flattened, frondlike sprays by branching from lateral leaf pairs, horizontal or drooping with upturned tips. Adult scale leaves on branchlets 1.5-3 mm long (to 5 mm on main shoots), light green at first, darkening to brownish green with age, occasionally with conspicuous, whitish, small stomatal patches, strongly differentiated into lateral and facial pairs, both types keeled, obscurely glandular. Tips of scale leaves elongate, narrowly and sharply triangular, loosely pointed forward or somewhat spreading, those of the facial leaves overlapping the base of the pair above them. Pollen cones 2.5-3.5 mm long, 2-2.5 mm wide, with five or six pairs of pollen scales, each with two (or three) pollen sacs. Seed cones nearly spherical, 9-12 mm in diameter, greenish brown at maturity, shiny or somewhat dulled by wax, with two (or three) pairs of seed scales, each with a prominent, pale, triangular point on the face. Seeds one to three per scale, 4.5-6 mm long, light brown or reddish brown, the wings about as broad as the body.

Golden Vietnamese cypress caused a considerable stir when it was formally described in 2002 because it was assigned to a new genus. Unlike the two famous conifer genera first described in the middle and late 20th century, Metasequoia from China and Wollemia from Australia, the proposed Xanthocyparis was founded not just on a newly described species but also on another one that has been known for almost 200 years, Alaska yellow (Cupressus nootkatensis). Unfortunately, because Alaska yellow cedar, is the type and only species of a much earlier described genus, Callitropsis Oersted, Xanthocyparis is nomenclaturally superfluous and cannot be used for these two species if they are placed in a genus separate from Cupressus. The relationships of Vietnamese and Alaska yellow cedars are somewhat uncertain. While they are placed in Cupressus here, in line with several aspects of their morphology and biochemistry, their ability to cross with other species of Cupressus, and some DNA studies, other work suggests a more complicated picture in which each could represent a separate genus. Alternatively, since DNA studies show that they are most closely linked to the New World cypresses, if the latter were treated as a separate genus from the Old World cypresses, Alaska and Golden Vietnamese cypress would be placed in the New World genus even though they have two cotyledons like the Old World species. Even if each species were placed in its own genus, the name Xanthocyparis is not technically available, and Golden Vietnamese cypress would either need a new generic name or Xanthocyparis would have to be protected from the rules of nomenclature by formally conserving it nomenclaturally. The species itself requires urgent conservation action in the ordinary sense because it has been locally overexploited for its very fine, fragrant timber. The few hundred known remaining trees are generally in sites where it is too hard to cut them and remove the timber. Although searches in the vicinity of the known stands since 1999 had not revealed additional populations by the time the species was described in 2002.

Known only from the Bat Dai Son (mountains) in northern Ha Giang province, Vietnam. Scattered in mixed cloud forests on steep, rocky slopes and ridge tops with thin soils developed from limestone; 1,000-1,600 m.

 

Conservation Status

Red List Category & Criteria: Endangered

Cupressus vietnamensis has previously been assessed as Critically Endangered on the basis of its very restricted extent of occurrence (EOO), area of occupancy (AOO) and continuing decline. The new localities that have been discovered since 1999 (Cao Bang, Tuyen Quang in Viet Nam and Guangxi in China) have extended its known EOO to about 16,000 km2 which is beyond the threshold for Endangered but within that for Vulnerable. However, while the new localities have increased its AOO beyond the 10 km2 threshold for Critically Endangered, it is still much less than the threshold for Endangered (<500 km2). Although Cupressus vietnamensis is now known from 5-6 locations, it is still considered to be severely fragmented. There is an ongoing decline in the quality of habitat and probably the number of mature individuals especially within the smaller subpopulations in Viet Nam. On this basis an overall assessment of Endangered under the criteria for B2 is warranted. A new assessment may be required if further subpopulations are discovered in China or Vietnam.

Cupressus vietnamensis was originally discovered in the Bat Dai Son Mountains of northern Hagiang Province in Viet Nam. Since that discovery, very small subpopulations have also been found in two other provinces in northern Vietnam (Cao Bang and Tuyen Quang). More recently a single tree has been reported from the Mulun Nature Reserve in Guangxi, China (Wei Bin Xu, Guangxi Institute of Botany, pers. comm. April 2012). The true extent of its distribution in China is currently unknown. Based on current information the extent of occurrence is estimated to about 16,500 km2. The area of occupancy is uncertain but it is assumed to be more than 10 km2 but much less than 500 km2. There are 5-6 locations and the subpopulations are severely fragmented.

Surveys within Vietnam indicate that the total number of mature individuals is probably between 500 and 1,000 with the majority in the Bat Dai Son area. To date, only a single tree has been recorded from Guangxi although it is highly probable that there are more. The overall population trend is thought to be declining.

This small to medium sized tree (10-15 m) grows on the ridges and summits of karst limestone formations (very steep mountains) in elfin forest (cloud forest). In Guangxi it has been recorded from an altitude of 720 m a.s.l whereas in Vietnam it generally occurs between 1,000 and 1,600 m a.s.l. It occurs together with other conifers (the dominant species is Pseudotsuga sinensis) and small-leaved angiosperms, numerous epilithic and epiphytic orchids, ferns, mosses, etc.

Wood cutting is the main threat. The wood of Cupressaceous conifers, as well as its foliage, is sought after in eastern Asian culture. The lower slopes are being heavily deforested for the expansion of agriculture, but this is unlikely to reach the ridges. But firewood cutting and cutting for other purposes (this species produces a fine, yellow-brown very hard, fragrant timber) evidently does occur in some areas. Due to the lack of transport facilities and other factors, most of the timber has been traded locally. Estimates of population decline cannot be made at this stage given our current knowledge. Locally used for house construction.

In Vietnam the majority of the national population occurs with the Bat Dai Son and Na Hang nature reserves. This species has also been added to Group IA of the National List of Rare and Precious Flora and Fauna which prohibits any exploitation. An ex situ conservation programme has been initiated and some restoration work undertaken in the Bat Dai Son area. In China, this species is only known from one nature reserve.

 

References

  • Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  • Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
  • IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.

Product CodeXAN3OONG40
Weight1.5 kg
Height20 - 25 cm
DepthCutting


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