Picea retroflexa
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Picea retroflexa is a species fromthe pine family (Pinaceae). It is native to China and is considered by some authors to be a variety of the bristle spruce ( Picea asperata ).
description
Picea retroflexa grows as an evergreen tree that can reach heights of growth of up to 45 meters and diameters of up to 1 meter at chest height . The gray-brown trunk bark is furrowed and divided into irregularly large, rough plates. The smooth or slightly hairy bark of the branches is initially red or yellow-brown and turns brown or brownish gray into the second year.
The resinous winter buds are conical to conical-ovoid. With a length of 1 to 2 centimeters and a width of 0.1 to 0.2 centimeters, the slightly curved needles are linear with a tapering upper end and have a square to diamond-shaped cross section. There are four to eight stoma lines on each needle side .
Picea retroflexa is monoecious, separate sexes ( monoecious ). The flowering period in China extends from April to May. The cones are elongated-elliptical to cylindrical in shape with a length of 5 to 16 centimeters and a diameter of 2.5 to 3.5 centimeters. The initially green cones turn light brown to reddish brown as they ripen in September or October. The seed scales rarely have a two-lobed tip, are obovate and about 2 centimeters long and 1.5 centimeters wide. Their margins are whole, rarely also slightly serrated. The seeds, which are elliptical with a length of about 4 millimeters, have an oblong, obovate wing with a length of about 11 millimeters.
The number of chromosomes is 2n = 24.
Distribution and location
The natural range of Picea retroflexa is in China. It includes Helan Shan in northern Ningxia , eastern and southern Gansu , southwest Shaanxi , western Sichuan , southeast Xizang and Qinghai .
Picea retroflexa thrives at altitudes of 2400 to 4700 meters. It is a tree species of the continental alpine climate with low annual precipitation. It grows mainly on northern slopes with acidic soils . At low altitudes, mixed stands of the Schensi fir ( Abies chensiensis ), the Chinese red birch ( Betula albosinensis ), Picea aurantiaca , the Likiang spruce ( Picea likiangensis ) and the Chinese hemlock ( Tsuga chinensis ) are found. At higher altitudes, Picea retroflexa forms pure stands or grows together with the common fir ( Abies squamata ).
Picea retroflexa is classified as "critically endangered" in the IUCN Red List . The stocks have shrunk by 50 to 70 percent in the past. The main reason given is uncontrolled logging in the 1950s to the 1990s. The Chinese government recently banned logging in western China to protect this species. In addition to the felling, fires are a particular danger. Furthermore, pasture activity reduces the natural regeneration.
Systematics
Picea retroflexa is assigned to the subgenus Picea , the section Picea , the subsection Picea and the series Asperatae within the genus of the spruce trees ( Picea ) .
It was first described as Picea retroflexa in 1906 by Maxwell Tylden Masters in Journal of the Linnean Society, Botany , Volume 37 (262), page 420. It is viewed by some authors as a variety of the bristle spruce ( Picea asperata ).
swell
- Christopher J. Earle: Picea retroflexa. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed on July 20, 2013 .
- Liguo Fu, Nan Li, Thomas S. Elias & Robert R. Mill: Pinaceae . Picea. In: Wu Zhengyi, Peter H. Raven & Hong Deyuan (eds.): Flora of China . Cycadaceae through Fagaceae. Volume 4. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis 1999, ISBN 0-915279-70-3 , Picea asperata var. Asperata , p. 28 (English, Picea asperata var. Asperata - online - this printed work is online with the same text).
Individual evidence
- ↑ a b c d e Liguo Fu, Nan Li, Thomas S. Elias & Robert R. Mill: Pinaceae . Picea. In: Wu Zhengyi, Peter H. Raven & Hong Deyuan (eds.): Flora of China . Cycadaceae through Fagaceae. Volume 4. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis 1999, ISBN 0-915279-70-3 , Picea asperata var. Asperata , p. 28 (English, Picea asperata var. Asperata - online - this printed work is online with the same text).
- ↑ a b Picea retroflexa at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed August 1, 2016.
- ↑ Christopher J. Earle: Picea retroflexa. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed on July 20, 2013 .
- ↑ a b Picea retroflexa in the endangered Red List species the IUCN 2013 Posted by: D. Zhang, N. Li, T. Katsuki & K. Rushforth, 2010. Accessed July 20, 2013.
- ↑ Picea retroflexa. In: The Plant List. www.theplantlist.org, accessed July 20, 2013 (English).