Xanthocyparis vietnamensis
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Xanthocyparis vietnamensis |
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| Farjon & Hiep |
Xanthocyparis vietnamensis is a species of the cypress family (Cupressaceae). It wasdiscoveredin Vietnam in 1999. It is characterized by the simultaneous occurrence of youth and adult leaves on the same branch. The scientific name means "Vietnamese golden cypress" and refers to the homeland of the species and the color of the wood.
features
Appearance and bark
Xanthocyparis vietnamensis is a small to medium-sized tree that reaches heights of 10 to 15 meters. The trunk is monopodial , twisting and has a diameter of up to 50 centimeters. The bark is smooth and thin on branches, purple to red-brown, and flakes off in thin scales and strips. On the trunk of larger trees, the bark becomes soft and fibrous, brown to gray-brown, and flakes off in numerous thin strips. The branches are long and stick out horizontally. There are numerous leafy branches that stand in horizontal, overlapping layers or hang down slightly. They form a pyramidal crown in young trees, which becomes expansive and irregular in older trees.
leaves
The leaves of adult trees are predominantly the adult forms, but there are also youth leaves and transitional forms on adult trees.
The youth leaves are needle-shaped and stand in four- whorls on the branches, the same shape, the free, distal part is at an angle of 90 ° from the axis and is 15 to 20 millimeters long, 1.5 to 2 millimeters wide. The proximal part that runs down the axis is around 4 to 5 millimeters long. The leaves are linear, with entire margins and taper to a fine point. The stomata are in two whitish bands on the underside of the leaf. In these bands they form six to seven irregular rows parallel to the leaf axis. Transitional leaves are already similar to the adult leaves, but are 5 to 7 millimeters longer, lanceolate and protrude at a 45 ° angle. The adult leaves are scale-shaped. They stand opposite to one another, run down the axis for a short time, and are arranged in roof tiles. On the last and penultimate side branches they are 1.5 to 3 millimeters long and 1 to 1.3 millimeters wide. The side leaves are a little longer than the others. The latter are narrow oval-rhombic, keeled, pressed, their edge is serrated to the entire edge to the pointed to pointed end. The proximal part of the lateral leaves runs downwards, the distal part protrudes freely from the axis at an angle of 30 °, and is straight to sickle-shaped. The leaf margin is serrated, with entire margins towards the pointed to piercing end. The stomata of the adult leaves are inconspicuous, mainly on the upper side of the leaf and covered by a layer of wax. The glands are inconspicuous and are mainly located in depressions below the keeled distal part of the leaves.
Cones and seeds
The male, pollen-forming cones are 2.5 to 3.5 × 2 to 2.5 millimeters in size, oval to round, have 10 to 12 microsporophylls around 1 × 1 millimeter in size. Its edge is serrated, the tip is spiky. They are green and later turn yellow-brown. Each microsporophyll carries two large, spherical, yellow microsporangia . The pollen is spherical.
The female cones are solitary, less often in twos or threes on the outer edge, or near the base of the branches covered with adult leaves. The cones take two years to mature. They are initially green, later they turn dark to dull brown. They are approximately spherical and open 9 to 11 × 10 to 12 millimeters in size. Some remain on the plant after the seed has fallen out. The bract-scale complexes are in two, rarely three cross-opposed pairs. There are seldom irregular or reduced cones. The complexes are valve-shaped to approximately shield-shaped. The lower pair is elongated, widest at the distal end, the outer edge is rounded, but irregular. The outer surface is smooth at first, later it becomes wrinkled or furrowed radially. The furrows assume a distinct, 1 to 2.5 millimeter long umbo . The inner surface of the complex is red-brown, the seed scars are white or gray. Each fertile bract has one to three ovules , with six scales per cone, the two upper ones are sterile. A maximum of eight to nine seeds per cone mature.
The seeds are egg-shaped or irregularly shaped, flattened and 4.5 to 6 × 4 to 5 millimeters in size and 1.5 to 2 millimeters thick, including two lateral wings. The seed is light to red-brown, has a white hilum at the base and the micropylene beak is often preserved at the tip . The seed wings are 0.5 to 1 millimeter wide, thin, membranous and lighter than the seed.
Distribution and locations
Xanthocyparis vietnamensis occurs very locally in northern Vietnam in the province of Hà Giang . Here in the Bat Dai Son Mountains near the Chinese border, it thrives at altitudes of 1060 to 1180 meters.
It grows there in mixed deciduous-conifer-cloud forests. Amentotaxus argotaenia , Nageia wallichiana , Pseudotsuga sinensis , Podocarpus pilgeri and Taxus chinensis are found on conifers . The main deciduous trees are species of the genera Acer , Carpinus , Lithocarpus , Quercus and Ulmus , Pistacia weinmannifolia and Platycarya strobilacea are also common . Elaeocarpus , Eriobotrya , Sorbus and Schefflera are particularly found in the second tree layer . The shrub and herb layer is very species-rich, in the latter orchids are very common, as are ferns and mosses .
The limestone ridges on which Xanthocyparis vietnamensis grows are badly eroded. There are small earth-filled pockets between marble-like, weather-resistant rocks. The climate is subtropical and humid to wet for most of the year. The annual average temperature is between 14 and 18 ° C, the annual precipitation is 2000 to 2400 mm.
use
The wood is very hard, yellow-brown and fragrant. It is high quality but is only used locally due to the lack of transportation.
Danger
Xanthocyparis vietnamensis was classified as critically endangered shortly after its discovery ; this was not changed even after new populations were found. The area of the species was initially estimated to be less than 10 km², in 2004 only around 560 individuals were known. In 2006 it was almost 15 km² and around 600 individuals. The main hazard comes from felling. Clearing for agriculture poses no threat as the steep mountain ridges on which the species grows are unsuitable for agriculture.
history
The species was discovered in 1999 and initially invalidly described as a new species of the genus Thuja . In 2002 it was first described as a new species and genus Xanthocyparis vietnamensis .
supporting documents
- A. Farjon, Nguyen Tien Hiep, DK Harder, Phan Ke Loc, L. Averyanov: A New Genus and Species in Cupressaceae (Coniferales) from Northern Vietnam, Xanthocyparis vietnamensis . Novon, Vol. 12, 2002, pp. 179-189.
Individual evidence
- ↑ a b c Jacinto C. Regalado, Jr., Phan Ke Loc, Nguyen Tien Hiep, To Van Thao, Leonid V. Averyanov: The Vietnamese Golden Cypress (Xanthocyparis vietnamensis) Conservation Status Assessment (CSA) and Conservation Action Plan (CAP) . Fauna and Flora International, Hoang Lien Son Project, Hanoi 2006. (pdf; 386 kB) ( Memento from October 10, 2009 in the Internet Archive )
- ^ A. Farjon, Nguyen Tien Hiep, DK Harder, Phan Ke Loc, L. Averyanov: A New Genus and Species in Cupressaceae (Coniferales) from Northern Vietnam, Xanthocyparis vietnamensis . Novon, Vol. 12, 2002, pp. 179-189.
- ↑ Xanthocyparis vietnamensis in the endangered Red List species the IUCN 2004. Posted by: Farjon et al. . Retrieved August 12, 2009.
Web links
- Xanthocyparis vietnamensis in the endangered Red List species the IUCN 2004. Posted by: Farjon et al. . Retrieved May 11, 2006.
- Cupressus vietnamensis on conifers.org (with numerous pictures)