Amentotaxus formosana
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Amentotaxus formosana is a species of the genus Amentotaxus inthe yew family (Taxaceae). The specific epithet refers to the origin of this species, to Formosa, the former name of Taiwan .
description
Vegetative characteristics
Amentotaxus formosana grows as an evergreen tree or shrub that can grow to heights of 10 meters and a trunk diameter ( BHD ) of up to 36 centimeters.
The leaves are arranged at a distance of about 6 millimeters from each other at angles of 55 to 70 ° on the branch, but appear to be arranged in two lines in one plane. The leaves are almost sessile (subsessil); if a petiole is present, it is only 1 millimeter long and relatively thick. The leathery, dark green leaf blades are oblong, lanceolate to sickle-shaped and 5 to 8.5 inches long and 0.5 to 1 inches wide. On the underside of the leaf, the two stomatal ligaments running parallel to the central rib, about 2 millimeters wide, are clearly recognizable and are very densely arranged with about 30 rows each. The tip of the leaf is elongated, pointed.
Generative characteristics
Like the other species of the genus, Amentotaxus formosana is dioeciously separated ( diocyte ), d. H. male and female flowers are not found together on one individual.
The male cones are located on annual twigs and contain three to four (rarely two or five) whorls , each of which can reach lengths of 2.5 to 3 centimeters. At the whorls there are usually four rows of 20 to 30 sporophyll stands. These are very close and irregularly cross-opposite on the axis of the whorl and have a spherical shape and are 2.5 to 3 millimeters in diameter. A sporophyll stand is composed of nine to twelve shield-like, round or triangular, 1.5 to 2 millimeter large sporophylls . When ripe, they bend up and release the wingless pollen located in 5 to 8 sporangia (pollen sacs) .
The female cones are located individually in the leaf axils and are planted up to 1.5 centimeters and spherical or egg-shaped. They can be up to 6.5 millimeters long by the time they are fertilized . The aril is reddish-yellow when ripe and completely encloses the seed except for its tip. The reddish-purple seeds are elongated-ellipsoid or egg-shaped-ellipsoid with a length of 2 to 2.5 centimeters and a width of 0.9 to 1.1 centimeters.
Occurrence and endangerment
Amentotaxus formosana is endemic to southern Taiwan . There it grows scattered at altitudes of 700 to 1500 meters in the tropical and subtropical rainforest, mostly in ravines or on cliffs. According to the IUCN , Amentotaxus formosana is critically endangered. Only four separate populations of no more than 250 fully grown trees are known. These are located in the districts of Taitung and Pingtung , on the mountains Dahanshan (大漢 山) in the "Dawushan Nature Reserve", Kutzulunshan (姑子 崙 山), Chachayalaishan (茶茶 牙 頓 山) in the "Chachayalaishan Major Wildlife Habitat" and Lilungshan (楠 山) .
Taxonomy
The first description of Amentotaxus formosana was made in 1952 by Hui-Lin Li in the Journal of the Arnold Arboretum , Volume 33, 2, pp 196-197. He differentiated the genus Amentotaxus argotaenia, which had previously been considered a monotype, into different species, based on the stands isolated from one another and the different leaf shapes.
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- Hsuan Keng: Aspects of morphology of Amentotaxus formosana with a note on the taxonomic position of the genus . In: Journal of the Arnold Arboretum . tape 50 , no. 3 , 1969, ISSN 0004-2625 , pp. 432-445 . Scanned online at botanicus.org.
- Liguo Fu, Nan Li, Robert R. Mill: Amentotaxus formosana . In: Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China . Volume 4: Cycadaceae through Fagaceae . Science Press / Missouri Botanical Garden Press, Beijing / St. Louis 1999, ISBN 0-915279-70-3 , pp. 93 (English).
- Christopher J. Earle: Amentotaxus formosana. In: The Gymnosperm Database. December 12, 2010, accessed October 29, 2011 .
- Dawu Taiwan Amentotaxus Nature Reserve. November 15, 2005, accessed October 29, 2011 .
Individual evidence
- ↑ Amentotaxus formosana in the endangered Red List species the IUCN 2011. Posted by: Conifer Specialist Group, 2000. Accessed October 29, 2011th
- ↑ Hui-Lin Li: The genus Amentotaxus . In: Journal of the Arnold Arboretum . tape 33 , no. 2 , 1952, pp. 192-198 .
