Amentotaxus assamica
Amentotaxus assamica is a medium sized coniferous tree of the genus kitten yew ( Amentotaxus ). The natural range is in the east of India. The species is listed in the IUCN Red List as endangered.
- 6.1 Literature
- 6.2 Notes and references
Description
Appearance
Amentotaxus assamica grows as evergreen, up to 20 meter high tree. The trunk branches already close to the ground. The Stammborke is smooth, whitish gray and peels off in thin flakes. The branches are horizontally or hang something. The leafy branches grow in ascending or horizontal, to constantly and at an angle of 25 ° to 70 ° on the road. They are square in cross-section to nearly terete and show alternating grooves, each of which connects two needles. Young shoots are in the first year and green color in the following years from greenish yellow to yellowish brown.
Buds and needles
The vegetative buds are conical and have ovate - triangular, pointed - stachelspitzige bud scales.
The needles grow in two rows and are starting at an angle of usually 45 ° to 80 ° from the branch. They are short-stalked, linear or linear - lanceolate, crescent-shaped or S-shaped bent from 2 usually 7 to 11 and rarely up to 15 inches long and from 4 usually 7 to 12 millimeters wide. The base is asymmetrical, the needle is tapered to the tip together towards the tip is sharp - pointed. The needle edge is rolled flat or slightly down. The needles are leathery, but no sclerenchyma cells will be formed. The Needles are dark green, smooth or finely wrinkled. The bottom shows two white, thick wax -covered slit aperture strips of numerous stomata scattered distributed separated from each other by the central rib and by two broad bands of the green needle edge. The gap opening strips are 1.5 to 2 times wider than the green edge strip. The midrib is significantly increased on the needle top and is located in a 0.4 to 0.7 mm wide, shallow furrow. On the underside of the needle midrib is only slightly increased, and 1 to 1.8 millimeters wide.
Cones and seeds
The pollen cones are arranged in 4 to 4.5 cm long racemes of 8-10 Zapf pairs. Most grow two to four grapes together on a branch, rarely do they grow individually. The cones are ovoid and 3-5 millimeters long. The six to eight Mikrosporophylle are shield-shaped and each carry two to four pollen sacs.
The seed -bearing structures grow singly in the axils of the needles near the ends of the branches arranged decussate to a 1.5 to 2.5 centimeters long stem with eight ovoid, 2.5 to 5 mm long and 2.5 to 5 millimeters wide, keeled bracts. The aril is obovate -oblong to ellipsoid, mucronate, 25-35 mm long and has a diameter of 15 to 25 millimeters. He is initially glossy green and turn yellow to purple later. The real seed is oblong or elliptical, and a length of 15 to 20 mm and a diameter of 7-10 mm significantly smaller than the aril. He has a small, stachelspitziges end.
Distribution and ecology
The natural range of Amentotaxus assamica located in the Indian state of Arunachal Pradesh. The species grows in temperate warm rain forests on the northern slopes of the mountains at altitudes of 1600-2000 meters. They are found in forests with thick moss-covered trees of various species of oak (Quercus ), various representatives of the apparent chestnut ( Castanopsis ), maples (Acer) and rhododendron (Rhododendron ) are dominated. Furthermore, representatives of the magnolias (Magnolia ) grow in the forests, species of the genus Michelia, the Winter Hazel Corylopsis himalayana, Betula alnoides, Carpinus viminea and Exbucklandia populnea.
Threats and conservation
In the IUCN Red List Amentotaxus assamica is listed as endangered ( " Endangered "). Where known, the nature a distribution area ( " extent of occurrence" ) of less than 1,000 square kilometers, there are stocks on an area of less than 300 square kilometers ( "area of occupancy "). You know the kind of only two or three areas: from the Turoo Mountains, from the Delei Valley and another valley in the Dafla Mountains. There may also stocks in neighboring China, but these could not be operated. There is a continuing decline in stocks, for example, by conversion of forests into agricultural land by cutting down trees to use the wood and by the construction of roads and hydroelectric plants.
Systematics and etymology
Amentotaxus assamica is a species in the genus of yew kitten ( Amentotaxus ). It was first described in 1985 by David Kay Ferguson in Journal of Botany, British and Foreign. John Silba placed the taxon in 1990 as Amentotaxus yunnanensis var assamica ( DKFerguson ) Silba the type Amentotaxus yunnanensis to, but differs from this species and also all the other kittens yew by the lack of sclerenchyma cells, giving the needles a smoother surface. James Eckenwalder ordered in 2009 the taxon as a variety Amentotaxus Argotaenia var assamica ( DKFerguson ) Eckenwalder to Amentotaxus Argotaenia. Both assignments are not accepted and thus only synonyms, they are used by any Aljos Farjon nor by the IUCN.
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 refers to the area assamica Assam to which the state of Arunachal Pradesh was expected.
Use
There are no reports of a specific use of Amentotaxus assamica.