Amentotaxus hatuyenensis
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Amentotaxus hatuyenensis is a shrubby conifer from the genus of the catkins ( Amentotaxus ). The natural range of the species is in Vietnam.
description
Appearance
Amentotaxus hatuyenensis grows as an evergreen , 4 to 5 meter high shrub . The leafy twigs are thin, stalk-round and show alternating grooves that connect two needles. They are initially green, later yellowish, and then pale brown.
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 70 ° to 90 ° from the branch. They are almost sessile or have a short stalk, lanceolate, usually straight or sometimes slightly curved in a sickle shape, 4 to 7 centimeters long and 7 to 13 millimeters wide. The base is broadly wedge-shaped to blunt, the needle tapers conically towards the pointed tip. The edge of the needle is slightly curled down. The needles are light green to green, leathery and they form sclerenchymal cells , which make the top of the needle speckled and wrinkled. The underside of the needle shows two initially white or yellowish and later reddish brown to 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 sometimes 4 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 central rib is raised and 1 to 1.5 millimeters wide.
Cones and seeds
The pollen pins are about 10 centimeters long grapes arranged from 10 to 15 pin pairs. Usually three to five grapes grow together on one branch. The cones are round and about 3.5 millimeters long. The eight to ten microsporophylls are shield-shaped and each carry five to eight small pollen sacs .
The structures carrying the seeds grow individually in the axils of the needles near the ends of needled branches on a stalk about 1.5 centimeters long with ten to twelve cross-opposed, keeled cover scales that enclose the individual ovules . The aril surrounding the seed is only known when it is immature.
Distribution and ecology
The natural range of Amentotaxus hatuyenensis is in Vietnam in the provinces of Hà Giang and Hà Tuyên . The species is rare and grows on steep mountain ranges of the limestone mountains at altitudes of 1000 to 1500 meters. Fog and rain are frequent, and the annual rainfall is over 1,800 millimeters. The mean temperatures are between 15 and 18 ° Celsius. In the few areas where the species has been found, it grows together with conifers such as Pinus fenzeliana , the Chinese hemlock ( Tsuga chinensis ), Amentotaxus yunnanensis , Cephalotaxus mannii , Xanthocyparis vietnamensis , Nageia fleuryi , Podocarpus neriifolius and Podocarpus neriifolius trees such as Podocarpus pilgeri Representatives of the maples ( Acer ), the hornbeams ( Carpinus ), the genus Lithocarpus , the oaks ( Quercus ) and the elms ( Ulmus ). The trees are densely overgrown with epiphytes such as mosses , ferns and orchids .
Hazard and protection
In 2010 , Amentotaxus hatuyenensis was listed as “Endangered” on the IUCN Red List . Only about 250 fully grown specimens were known, whose habitat deteriorated further due to the continued felling of the forests and fires. The stocks also appeared to be recovering poorly. However, there was a population in the protected Bat Dai Son nature reserve, which was established to protect the newly discovered species Xanthocyparis vietnamensis .
In the meantime, the species is listed by the IUCN as being common with Amentotaxus yunnanensis , which was classified as endangered ("Vulnerable") in 2017.
Systematics and Etymology
Amentotaxus hatuyenensis is a species from the genus of the catkins ( Amentotaxus ). It was only in 1996 by Tiên Hiep Nguyên in Flore du Cambodge du Laos et du Vietnam firstdescribed . Synonyms are not known. The species differs only slightly from Amentotaxus yunnanensis and Amentotaxus poilanei . The most important difference to Amentotaxus yunnanesis is the color of the stomata on the underside of the needle, which is white in young needles of both species, later turns yellow in Amentotaxus yunnanesis and reddish to brown in Amentotaxus hatuyenensis . The leaf shape of the type specimen is rather lanceolate, but there is hardly any knowledge about the range of variations of the needle shape. The differences are so small that Aljos Farjon suggests that the taxon should be included as a variety Amentotaxus yunnanesis . James E. Eckenwalder sees the name Amentotaxus hatuyenensis only as a synonym of Amentotaxus yunnanesis and does not give the representatives the status of a variety.
The generic name Amentotaxus is derived from the Latin amentum for “throwing belt”, but also botanically “kitten”, and from taxus , the Latin name of the yew tree. He thus refers to the cluster-shaped arrangement of the pollen cones and corresponds to the German name "Kitteneibe". The specific epithet hatuyenensis is derived from the province of Hà Tuyên; Specimens from this area were the basis for the first description.
use
Nothing is known about the use of the species.
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, 173-174 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 147 .
- 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 d e f g h Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 173
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, pp. 173-174
- ^ A b Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 173
- ↑ a b Amentotaxus yunnanensis in the IUCN Red List of Threatened Species .
- ↑ Amentotaxus hatuyenensis. In: The International Plant Name Index. Retrieved January 6, 2014 .
- ↑ Amentotaxus hatuyenensis. In: The Plant List. Retrieved January 6, 2013 .
- ↑ James E. Eckenwalder: Conifers of the World , p. 147
- ↑ Exactly: Etymological Dictionary of Botanical Plant Names , p. 56
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 168
Web links
- Amentotaxus hatuyenensis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed January 5, 2014.
- Amentotaxus hatuyenensis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
- Christopher J. Earle: Amentotaxus hatuyenensis. In: The Gymnosperm Database. www.conifers.org, November 24, 2012, accessed January 5, 2014 (English).