Amentotaxus assamica

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Amentotaxus assamica
Systematics
Subdivision : Seed plants (Spermatophytina)
Class : Coniferopsida
Order : Conifers (Coniferales)
Family : Yew family (Taxaceae)
Genre : Kitten slices ( Amentotaxus )
Type : Amentotaxus assamica
Scientific name
Amentotaxus assamica
DKFerguson

Amentotaxus assamica is a medium-sized conifer from the genus of the catkins ( Amentotaxus ). The natural range is in the east of India. The species is listed as critically endangered onthe IUCN Red List .

description

Appearance

Amentotaxus assamica grows as evergreen , up to 20 meters high tree . The trunk branches out close to the ground. The trunk bark is smooth, whitish gray and flakes off in thin flakes. The branches are horizontal or hang a little. The leafy branches grow upwards or horizontally, opposite and at an angle of 25 ° to 70 ° on the branch. They are angular to almost stem-round in cross-section and show alternating grooves that connect two needles. Young shoots are green in the first year and turn from greenish yellow to yellowish brown in the following years.

Buds and needles

The vegetative buds are conical and have egg-shaped-triangular, pointed-prickly-pointed bud scales.

The needles grow in two lines and are usually at an angle of 45 ° to 80 ° from the branch. They are short-stalked, linear or linear-lanceolate, sickle-shaped or S-shaped, from 2 mostly 7 to 11 and rarely up to 15 centimeters long and from 4 mostly 7 to 12 millimeters wide. The base is asymmetrical, the needle tapers conically towards the point, the point is pointed-pointed. The edge of the needle is flat or slightly rolled down. The needles are leathery, but no sclerenchymal cells are formed. The top of the needle is dark green, smooth or finely grooved. The underside shows two white, thickly wax-covered stomata bands made up of numerous scattered stomata that are separated from each other by the central rib and from the needle edge by two broad green bands. The stomata are 1.5 to 2 times wider than the green marginal strips. The midrib is significantly raised on the upper side of the needle and lies in a 0.4 to 0.7 millimeter wide, shallow groove. On the underside of the needle, the central rib is only slightly raised and 1 to 1.8 millimeters wide.

Cones and seeds

The pollen cones are arranged in 4 to 4.5 centimeter long clusters of 8 to 10 pairs of cones. Usually two to four grapes grow together on one branch, rarely they also grow individually. The cones are egg-shaped and 3 to 5 millimeters long. The six to eight microsporophylls are shield-shaped and each carry two to four pollen sacs .

The seed-bearing structures grow individually in the axils of the needles near the ends of the branches on a 1.5 to 2.5 centimeter long stem with eight cross-opposed, egg-shaped, 2.5 to 5 millimeters long and 2.5 to 5 millimeters wide, keeled deck shed. The aril is obovate-oblong to ellipsoidal, spiky, 25 to 35 millimeters long and has a diameter of 15 to 25 millimeters. It is initially glossy green and later turns yellow to purple in color. The actual seed is elongated or ellipsoidal and, with a length of 15 to 20 millimeters and a diameter of 7 to 10 millimeters, significantly smaller than the aril. It has a small, spiked end.

Distribution and ecology

The natural range of Amentotaxus assamica is in India in the state of Arunachal Pradesh . The species grows in warm temperate rainforests on the northern slopes of the mountains at altitudes of 1600 to 2000 meters. They are found in forests with heavily moss-covered trees, which are dominated by different types of oak ( Quercus ), different representatives of the pseudo-chestnut ( Castanopsis ), maple species ( Acer ) and rhododendrons ( Rhododendron ). Furthermore, representatives of the magnolias ( Magnolia ), species of the genus Michelia , the false hazel Corylopsis himalayana , Betula alnoides , Carpinus viminea and Exbucklandia populnea grow in the forests .

Hazard and protection

In the Red List of the IUCN is Amentotaxus assamica as endangered ( "Endangered") out. As far as known, the species has an area of ​​distribution ("extent of occurrence") of less than 1000 square kilometers, stocks exist in an area of ​​less than 300 square kilometers ("area of ​​occupancy"). The species is only known from two or three areas: from the Turoo Mountains, from the Delei Valley and another valley in the Dafla Mountains. There may also be stocks in neighboring China, but these could not be activated. There is a continued decline in stocks, for example through the conversion of forests into agricultural land, through the felling of trees to use the wood and through the construction of roads and hydroelectric plants.

Systematics and Etymology

Amentotaxus assamica is a species from the genus of the catkins ( Amentotaxus ). It was only in 1985 by David Kay Ferguson in the Journal of Botany, British and Foreign firstdescribed . John Silba ordered the taxon in 1990 as Amentotaxus yunnanensis var. Assamica (DKFerguson) Silba the type Amentotaxus yunnanensis to, but different from this kind and all other amentotaxus by the lack of sclerenchyma, giving a smoother surface of the needles. In 2009 James Eckenwalder assigned the taxon as the variety Amentotaxus argotaenia var. Assamica (DKFerguson) Eckenwalder to Amentotaxus argotaenia . Both classifications are not recognized and therefore only synonyms , they are neither used by Aljos Farjon nor by the IUCN.

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 assamica refers to the area Assam, to which the state of Arunachal Pradesh was counted.

use

There have been no reports of specific uses for Amentotaxus assamica .

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, 170-171 .
  • James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 145 .
  • 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

  1. ↑ a b c d Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 170
  2. ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, pp. 170-171
  3. ↑ a b c d e f Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 171
  4. ↑ a b Amentotaxus assamica in the Red List of Threatened Species of the IUCN 2013. Posted by: P. Thomas, W. Liao, Y. Yang, 2010. Retrieved on January 5, 2014.
  5. ↑ Amentotaxus assamica. In: The International Plant Name Index. Retrieved January 5, 2014 .
  6. ↑ Amentotaxus yunnanensis var. Assamica. In: The International Plant Name Index. Retrieved January 6, 2014 .
  7. ↑ James E. Eckenwalder: Conifers of the World , p. 145
  8. ↑ Amentotaxus argotaenia var. Assamica. In: The International Plant Name Index. Retrieved January 6, 2014 .
  9. ↑ Exactly: Etymological Dictionary of Botanical Plant Names , p. 56
  10. ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 168

Web links

  • Amentotaxus assamica at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed January 5, 2014.
  • Amentotaxus assamica in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
  • Amentotaxus assamica. In: The Plant List. Retrieved January 5, 2013 .
  • Christopher J. Earle: Amentotaxus assamica. In: The Gymnosperm Database. www.conifers.org, November 24, 2012, accessed January 5, 2014 (English).