Amentotaxus yunnanensis
Amentotaxus yunnanensis in the Lyman Plant House, Smith College, Northampton, Massachusetts
Amentotaxus yunnanensis is a coniferous tree from the kind of kitten yew ( Amentotaxus ). The natural range of the species is in Vietnam, China and Laos. It is listed in the IUCN Red List as endangered.
- 6.1 Literature
- 6.2 Notes and references
Description
Appearance
Amentotaxus yunnanensis grows achieved as evergreen, usually up to 25 times to 30 meter high tree, the trunk diameter of up to 80 centimeters ( diameter at breast height ). The Stammborke is brown, smooth and peels off in thin layers. The branches are spread or ascending, forming a broad crown. The needled branches growing against constantly at an angle of 45 to 80 degrees on the branches. You are ascending or spreading, terete and having alternate, spiral grooves, each connecting two bases needle. You are in the first year green and pale yellow color to yellowish brown in the following years.
Buds and needles
The vegetative buds are conical and have ovate - triangular, pointed bud scales.
The needles grow in two rows and are starting at an angle of 50 to 70 degrees from the branch. You are almost sitting up shortly stalked, lanceolate or linear, mostly straight or sometimes slightly curved sickle-shaped, from 3.5, however, usually 5 to 10 and sometimes up to 15 inches long and 8 to 12, sometimes to 15 millimeters wide. The base is broadly wedge -shaped to blunt needles and the narrowing itself to obtuse or more or less pointed tip. The needle edge is slightly rolled down. The needles are light green to green, leathery and make sclerenchyma cells, which spotted the needle top and makes wrinkled. The needle bottom shows two yellowish-white to pale brown stomatal strips from numerous stomata scattered distributed, which are separated by the midrib of each other and by two green bands from the needle edge. The gap opening strips are 2 to 3 times wider than the green edge strip. The midrib is significantly increased on the needle top and is located in a 0.8 to 1.0 mm wide, reaching to tip, shallow furrow. On the underside of the needle midrib is increased at least close to the needle base and 1 to 1.5 millimeters wide.
Cones and seeds
The pollen cones are arranged in 10 to 15 centimeters long racemes from twelve to twenty Zapf pairs. Most grow four to six grapes composed of a large axillary or almost terminal bud. The cones are round and about 3.5 millimeters long. The eight to ten Mikrosporophylle are shield-shaped and wear four to six and sometimes up to eight pollen sacs.
The seed -bearing structures ( seed cones) growing near the ends benadelter branches singly in the axils of needles arranged in decussate with eight to ten, keeled bracts, which individual on a thin, bent downwards, 1.5 to 2 cm long stem, terminal ovule enclose. The surrounding the seed aril is ellipsoidal or narrowly ovate, 22 to 26, sometimes to 30 mm long and has a diameter of 12-15 millimeters. He is smooth, bright red when ripe purple to reddish and has a stachelspitziges end. The seed itself is much smaller, about 18 millimeters long and 10 millimeters thick, oblong to ellipsoid and has a small stachelspitzige tip.
The pollen is released in April, the seeds ripen in October.
Distribution and ecology
The natural range of Amentotaxus yunnanensis is located in the north of Vietnam in the provinces Bắc Kan, Ha Giang, Ha Tuyen, Lào Cai, Nghe An and Thanh Hóa in China in Guizhou Province ( Xingyi ) and in Yunnan and Laos in the province Houaphan. Amentotaxus yunnanensis grows at altitudes 800-1600 m. The annual rainfall is about 1500 mm and fog are common in the area of distribution. The distribution area is the hardiness zone 9 attributed with mean annual minimum temperatures between -6.6 to -1.2 degrees Celsius ( 20-30 degrees Fahrenheit). The species usually grows as a small tree in the undergrowth and is scattered in deciduous forests with evergreen and deciduous trees. In Vietnam, he also reaches greater heights of growth and then extends into the crown region of evergreen broadleaf forests. The species is relatively tolerant and shade the seedlings grow successfully even under a closed canopy. Most of the surface is karst and one finds 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 deciduous trees. On siliceous rocks such as granite and gneiss, the kind often grows as a large tree under deciduous trees with just a few socialized conifers, such as Cephalotaxus mannii, Dacrycarpus imbricatus and Nageia wallichiana.
Threats and conservation
In the IUCN Red List Amentotaxus yunnanensis is listed as endangered ( " Vulnerable "). The stocks are likely to decline in the last 75 years by the conversion of forests into agricultural land and the timber production by 30 to 50 percent. Before you went from a strong threat from ( " Endangered " ) because the stocks in China have declined by more than 50 percent over the same period, and the distribution area in Vietnam was not known, which is now regarded as distribution area. Only a small part of the collection grows in protected areas.
Systematics and etymology
Amentotaxus yunnanensis is a species of the genus kitten yew ( Amentotaxus ). It was first described in 1952 by Li Huilin in the Journal of the Arnold Arboretum. Aljos Farjon no different varieties. James Eckenwalder assigns the representatives of the species Amentotaxus formosana and Amentotaxus poilanei as a variety Amentotaxus yunnanensis var formosana the type Amentotaxus yunnanensis to Amentotaxus hatuyenensis he sees not as a separate taxon and expects the representatives to the variety Amentotaxus yunnanensis yunnanensis var. A synonym of the species is Amentotaxus Argotaenia var bringing the representatives of Amentotaxus yunnanensis be attributed as a variety of the species Amentotaxus Argotaenia yunnanensis ( HLLi ) Keng f.
The genus name is derived from the Latin Amentotaxus amentum for " throwing belt " but also botanical "Kitten " from and taxus, the Latin name of " yew ". He thus refers to the grape-like arrangement of the pollen cones and corresponds to the German name " Kätzcheneibe ". The specific epithet yunnanensis refers to the Chinese province of Yunnan. Trees from this region were the basis for the first description of the type
Use
The wood of larger trees is used in China for the production of furniture, the wood of smaller trees are processed into tools. Probably the wood from trees grown in Vietnam is used in a similar manner. The seeds are rich in oils that are obtained for medical use. Amentotaxus yunnanensis is sometimes used as bonsai.