Amentotaxus yunnanensis
| Amentotaxus yunnanensis | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Amentotaxus yunnanensis in the Lyman Plant House, Smith College , Northampton , Massachusetts |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Amentotaxus yunnanensis | ||||||||||||
| HLLi |
Amentotaxus yunnanensis is a conifer from the genus of the catkins ( Amentotaxus ). The natural range of the species is in Vietnam, China and Laos. It is listed as endangered onthe IUCN Red List .
description
Appearance
Amentotaxus yunnanensis grows as evergreen , usually up to 25 times to 30 meter high tree , the trunk diameter of up to 80 centimeters ( diameter at breast height ) achieved. The trunk bark is brown, smooth and flakes off in thin layers. The branches are spread out or ascending and form a broad crown. The needled branches grow opposite to each other at an angle of 45 to 80 degrees on the branches. They are ascending or spreading out, have pedicels and alternating, winding grooves that connect two needle bases each. They are green in the first year and turn light yellow to yellowish brown in the following years.
Buds and needles
The vegetative buds are conical and have egg-shaped-triangular, pointed bud scales.
The needles grow in two lines and are at an angle of 50 to 70 degrees from the branch. They are almost sessile to short-stalked, lanceolate or linear, usually straight or sometimes slightly crescent-shaped, from 3.5 but usually 5 to 10 and sometimes up to 15 centimeters long and 8 to 12, sometimes up to 15 millimeters wide. The base is broadly wedge-shaped to blunt and the needles narrow to a blunt or more or less pointed tip. The edge of the needle is slightly curled down. The needles are light green to green, leathery and form sclerenchymal cells , which make the top of the needle speckled and wrinkled. The underside of the needle shows two yellowish-white to pale brown stomata from numerous scattered stomata, which are separated from each other by the midrib and from the edge of the needle by two green bands. The stomata are 2 to 3 times wider than the green marginal strips. The midrib is significantly raised on the upper side of the needle and lies in a 0.8 to 1.0 millimeter wide, shallow furrow reaching to the tip. On the underside of the needle, the midrib is raised at least near the base of the needle and 1 to 1.5 millimeters wide.
Cones and seeds
The pollen cones are arranged in 10 to 15 centimeter long clusters of twelve to twenty pairs of cones. Usually four to six grapes grow together from a large axillary or almost terminal bud. The cones are round and about 3.5 millimeters long. The eight to ten microsporophylls are shield-shaped and each carry four to six and sometimes up to eight pollen sacs .
The seed- bearing structures (seed cones) grow individually in the axils of the needles near the ends of the needled branches on a thin, downwardly curved, 1.5 to 2 centimeter long stalk with eight to ten keeled cover scales arranged opposite each other. enclose terminal ovule . The surrounding the seed aril is ellipsoidal or ovoid narrow, sometimes 22 to 26 to 30 millimeters long and has a diameter 12 to 15 millimeters. It is smooth, light red to reddish purple when ripe and has a spiky end. The seed itself is much smaller, about 18 millimeters long and 10 millimeters thick, oblong to ellipsoid and has a small spiky tip.
The pollen is released in April and the seeds ripen in October.
Distribution and ecology
The natural range of Amentotaxus yunnanensis is in the north of Vietnam in the provinces Bắc Kạn , Hà Giang , Hà Tuyên , Lào Cai , Nghệ An and Thanh Hóa , in China in the province Guizhou (in Xingyi ) and in Yunnan and in Laos in the province Houaphan . Amentotaxus yunnanensis grows at heights of 800 to 1,600 meters. The annual rainfall is over 1500 millimeters and fog is common in the distribution area. The distribution area is assigned to winter hardiness zone 9 with mean annual minimum temperatures of −6.6 to −1.2 degrees Celsius (20 to 30 degrees Fahrenheit ). The species usually grows as a small tree in the undergrowth and occurs scattered in deciduous forests with evergreen and deciduous trees. In Vietnam it also reaches greater heights and then extends into the crown region of evergreen deciduous forests. The species is comparatively shade-tolerant and the seedlings grow successfully even under a closed canopy. The subsoil is mostly karst and you can find Amentotaxus yunnanensis together with other conifers such as Fokiena hodginsii , Xanthocyparis vietnamensis , the Chinese Douglas fir ( Pseudotsuga sinensis ), Podocarpus neriifolius , Dacrydium elatum , the Chinese yew ( Taxus chinensis ) and with On silicate rocks such as granite and gneiss, the species often grows as a large tree under deciduous trees with only a few associated conifers such as Cephalotaxus mannii , Dacrycarpus imbricatus and Nageia wallichiana .
Hazard and protection
In the Red List of the IUCN is Amentotaxus yunnanensis as endangered ( "Vulnerable") out. Stocks have probably declined by 30 to 50 percent over the past 75 years as a result of the conversion of forests into agricultural land and logging. Previously, it was assumed that the population was endangered, as the population in China had declined by more than 50 percent in the same period and the distribution area in Vietnam, which is now viewed as the main distribution area, was not known. Only a small part of the population grows in protected areas.
Systematics and Etymology
Amentotaxus yunnanensis is a species from the genus of the catkins ( Amentotaxus ). It was first described by Li Huilin in 1952 in the Journal of the Arnold Arboretum . Aljos Farjon does not distinguish between varieties . James E. Eckenwalder assigns the representative of the types Amentotaxus formosana and Amentotaxus poilanei as a variety Amentotaxus yunnanensis var. Formosana the type Amentotaxus yunnanensis to, Amentotaxus hatuyenensis he does not see as a separate taxon and expects the representatives to the variety Amentotaxus yunnanensis var. Yunnanensis . Amentotaxus argotaenia var. Yunnanensis (HLLi) Keng f is a synonym of the species . whereby the representatives of Amentotaxus yunnanensis are assigned as a variety of the species Amentotaxus argotaenia .
The generic name Amentotaxus is derived from the Latin amentum for “throwing belt” but also botanically “kitten” and from taxus , the Latin name for “yew”. He thus refers to the cluster-shaped arrangement of the pollen cones and corresponds to the German name "Kitteneibe". The specific epithet yunnanensis refers to the Chinese province of Yunnan. Trees from this area were the basis for the first description of the species.
use
The wood of larger trees is used in China to manufacture furniture, the wood of smaller trees is processed into tools. Probably the wood of trees from Vietnam is used in a similar way. The seeds are rich in oils obtained for medicinal use. Amentotaxus yunnanensis is sometimes used as a bonsai .
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 1 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 168, 175-176 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 145-147 .
- Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China . Volume 4: Cycadaceae through Fagaceae . Science Press / Missouri Botanical Garden Press, Beijing / St. Louis 1999, ISBN 0-915279-70-3 , pp. 92 (English).
- Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Nikol, Hamburg 2005, ISBN 3-937872-16-7 , p. 56 (reprint from 1996).
Individual evidence
- ↑ a b c Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 175
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, pp. 175-176
- ↑ a b c d e f g Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 176
- ^ Liguo Fu, Nan Li, Robert R. Mill: Amentotaxus yunnanensis , in Flora of China , Volume 4, p. 92
- ↑ a b James E. Eckenwalder: Conifers of the World , p. 146
- ↑ Amentotaxus yunnanensis in the Red List of Threatened Species of the IUCN 2013. Posted by: P. Thomas, W. Liao, Y. Yang, 2010. Accessed on January 11, 2014.
- ↑ Amentotaxus yunnanensis. In: The International Plant Name Index. Retrieved January 11, 2014 .
- ↑ James E. Eckenwalder: Conifers of the World , p. 147
- ↑ Amentotaxus yunnanensis. In: The Plant List. Retrieved January 11, 2013 .
- ↑ Exactly: Etymological Dictionary of Botanical Plant Names , p. 56
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 168
Web links
- Christopher J. Earle: Amentotaxus yunnanensis. In: The Gymnosperm Database. www.conifers.org, November 24, 2012, accessed January 11, 2014 .
- Amentotaxus yunnanensis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed January 11, 2014.
- Amentotaxus yunnanensis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.