Amentotaxus hatuyenensis
Amentotaxus hatuyenensis is a shrub-like growing conifer of the genus kitten yew ( Amentotaxus ). The natural range of the species is located in Vietnam. It is listed in the IUCN Red List as endangered.
- 6.1 Literature
- 6.2 Notes and references
Description
Appearance
Amentotaxus hatuyenensis grows as evergreen, 4-5 m tall shrub. The leafy branches are thin, terete and show alternating grooves that connect two needles. They are initially green, later yellow and then brown pale.
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 70 ° to 90 ° from the branch. You are almost sitting up shortly stalked, lanceolate, mostly straight or sometimes slightly curved sickle-shaped, 4 to 7 inches long and 7 to 13 mm wide. The base is broadly wedge -shaped to obtuse, the needle is tapered to pointed tip together. The needle edge is slightly rolled down. The needles are light green to green, leathery and they make sclerenchyma cells, which spotted the needle top and makes wrinkled. The needle base is two initially white or yellowish and reddish brown to brown later gap opening strip of numerous stomata scattered distributed separated from each other by the central rib and by two green bands from the needle edge. The stomatal strips are 2 to 3 sometimes 4 times wider than the green border 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, and 1 to 1.5 millimeters wide.
Cones and seeds
The pollen cones are arranged in about 10 inches long racemes from 10 to 15 PTO pairs. Most grow three to five grapes together on a branch. The cones are round and about 3.5 millimeters long. The eight to ten Mikrosporophylle are shield-shaped and each carrying five to eight small pollen sacs.
The seed -bearing structures grow near the ends of branches benadelter individually in the axils of needles arranged in decussate with ten to twelve, keeled bracts which enclose the single ovule on an approximately 1.5 cm long stem. The surrounding the seed aril is known only in the immature state.
Distribution and ecology
The natural range of Amentotaxus hatuyenensis located in Vietnam in the provinces of Ha Giang and Tuyen Ha. The species is rare and grows on steep mountain ranges of limestone hills at altitudes from 1000 to 1500 meters. Fog and rain are common, and the annual rainfall is about 1800 mm. The average temperatures are from 15 to 18 ° Celsius. In the few areas where the species is found, it grows along with conifers, such as Pinus fenzeliana, the Chinese hemlock ( Tsuga chinensis), Amentotaxus yunnanensis, Cephalotaxus mannii, Xanthocyparis vietnamensis, Nageia fleuryi, Podocarpus neriifolius and Podocarpus pilgeri and deciduous trees such as representatives of maples ( Acer), the hornbeam (Carpinus ), the genus Lithocarpus, the oaks (Quercus ) and elm (Ulmus ). The trees are densely covered with epiphytes, such as mosses, ferns and orchids.
Threats and conservation
In the IUCN Red List Amentotaxus hatuyenensis is listed as endangered ( " Endangered "). There are only known approximately 250 adult specimens, their habitat is degraded by the continuing cases of forests and fires further. The holdings also appear to be poorly to recover. However, there is a population in the protected Bat Dai Son Nature Reserve, which was established to protect the newly discovered species Xanthocyparis vietnamensis.
Systematics and etymology
Amentotaxus hatuyenensis is a species in the genus of yew kitten ( Amentotaxus ). It was first described in 1996 by Hiep Nguyen Tiên in the Flore du Cambodge du Laos et du Vietnam. Synonyms are not known. The type differs only slightly from Amentotaxus yunnanensis and Amentotaxus poilanei. The most significant difference to Amentotaxus yunnanesis is the color of stomatal stripe on the needle base, which is in young needles of both species white, later yellowish discolored at Amentotaxus yunnanesis and Amentotaxus hatuyenensis reddish to brownish. The leaf shape of the type specimen is rather lanceolate, but there is little knowledge of the range of variation of the needle shape. The differences are so small that Aljos Farjon expresses the assumption that the taxon should be attributed as a variety Amentotaxus yunnanesis. James Eckenwalder sees the name Amentotaxus hatuyenensis only as a synonym of Amentotaxus yunnanesis and are the representatives nor the status of a variety.
The genus name is derived from the Latin Amentotaxus amentum for " throwing belt ", but also botanical " kitten ", and from taxus, the Latin name of the yew. He thus refers to the grape-like arrangement of the pollen cones and corresponds to the German name " Kätzcheneibe ". The specific epithet hatuyenensis derives from the province of Ha Tuyen; Specimens from this area were the basis of the first description.
Use
About the use of the type is not known.