Pseudotaxus chienii

Pseudotaxus chienii
Systematics
Subdivision :	Seed plants (Spermatophytina)
Class :	Coniferopsida
Order :	Conifers (Coniferales)
Family :	Yew family (Taxaceae)
Genre :	Pseudotaxus
Type :	Pseudotaxus chienii
Scientific name of the genus
	Pseudotaxus
	WCCheng
Scientific name of the species
	Pseudotaxus chienii
	(WCCheng) WCCheng

Pseudotaxus chienii is the only species of the monotypic plant genus Pseudotaxus withinthe yew family (Taxaceae). This rare and endangered species isnativeto China .

description

Vegetative characteristics

Pseudotaxus chienii grows as an evergreen shrub that can reach heights of up to 4 meters. The bark is gray-brown and flakes off in strips. The branches are almost lively. The bark of the branches is yellowish-green in the first year, later dark green. There are permanent bud scales at their base.

The leaves are arranged in a spiral around the branch at angles of 40 to 45 °, but appear to be arranged in two lines in one plane due to the bend at the base; with older shrubs, the angle ranges from 50 to 90 °. Petioles are less than 1 millimeter in length, or are absent. The non-leathery leaf blades are 1 to 2.6 inches long and 2 to 4.5 millimeters wide. In the first year, leaves are light green and inclined towards the branch axis. Later they get darker and are straight to slightly sickle-shaped. The midrib is slightly raised on both the top and bottom of the leaf. The white stoma bands are 0.5 to 1.1 millimeters wide and consist of 9 rows for younger and 13 to 19 rows for older shrubs. The upper end of the leaves is spiky, light green and up to 0.7 millimeters long.

Generative characteristics

Pseudotaxus chienii is dioecious separately sexed ( dioecious ), that means male and female flowers are not together on one individual. The sessile cones are single and axillary.

Male cones are round with a diameter of 3 to 4 millimeters and contain six to twelve shield-like sporophylls with four to six pollen sacs each . The aril is white when ripe bell-shaped and 5 to 7 millimeters long and encloses the single seed almost complete. The seed is egg-shaped with a small tip with a length of 5 to 8 millimeters and a diameter of 4 to 5 millimeters.

The pollination is carried out in China during the months of March to May and the seed is ripe in October.

The number of chromosomes is 2n = 24.

Occurrence and endangerment

Pseudotaxus chienii is native to southeastern China, including the Nanling Mountains ; in the north of the provinces of Guangdong and Guangxi , in the north-west and south of Hunan , in the south-west of Jiangxi and in the south of Zhejiang . The climate is temperate to subtropical, humid and characterized by the monsoons . Pseudotaxus chienii thrives in dense evergreen and deciduous laurel forests as an understory at altitudes of 700 to 1500 meters. This rare species occurs in limestone areas in ravines and on rock faces (tropical karst ).

In the IUCN's Red List of Endangered Species in 2010, Pseudotaxus chienii is classified as “Vulnerable”. Before 2010 it was considered "Endangered" = highly endangered. The reasons are the destruction of the habitats . Due to the strong fragmentation of the populations down to individual specimens, there is insufficient pollination. There is too little seed formation in the entire area .

Systematics

It was first described in 1934 under the name (Basionym) Taxus chienii by Wan Chun Cheng in Contributions from the Biological Laboratory of the Science Society of China, Sect. Bot. , Volume 9, Issue 3, p. 240. In 1947 Wan Chun Cheng noted in Research Notes, Forestry Institute; National Central University, Nanking. Dendrological Series 1 , page 1 the genus Pseudotaxus with the type species Pseudotaxus chienii . Another synonym for Pseudotaxus chienii (WCCheng) WCCheng is Nothotaxus chienii (WCCheng) Florin .

Populations from Guangxi were described by John Silba in 1996 as Pseudotaxus liiana due to the different morphology of the leaves. The differences could not be demonstrated significantly. Pseudotaxus liiana Silba and Pseudotaxus chienii subsp. liana (Silba) Silba are therefore also synonymous with Pseudotaxus chienii .

Pseudotaxus chienii is the only species of the genus Pseudotaxus in the tribe Taxeae within the family of Taxaceae .

use

The wood of Pseudotaxus chienii was used as wood carving. In the province of Zhejiang is Pseudotaxus chienii cultivated as an ornamental plant.

swell

Christopher J. Earle: Pseudotaxus chienii. In: The Gymnosperm Database. December 12, 2010, accessed November 12, 2011 .
Liguo Fu, Nan Li, Robert R. Mill: Taxaceae. : Pseudotaxus and Pseudotaxus chienii . 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. 91 (English). (Sections Description, Occurrence, Systematics and Use)

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Liguo Fu, Nan Li, Robert R. Mill: Taxaceae. : Pseudotaxus and Pseudotaxus chienii , p. 91 - online with the same text as the printed work , In: Wu Zheng-yi, Peter H. Raven (ed.): Flora of China. Volume 4: Cycadaceae through Fagaceae. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 1999, ISBN 0-915279-70-3 .

↑ Pseudotaxus chienii at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis}

↑ ^a ^b ^c ^d Pseudotaxus chienii in the IUCN Red List of Threatened Species 2019.1. Listed by: P. Thomas, Y. Yang, 2010. Retrieved May 11, 2019.

↑ ^a ^b ^c Pseudotaxus chienii at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed May 11, 2019.}

↑ Pseudotaxus chienii in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved May 11, 2019.}

^ John Silba: A new species of Pseudotaxus Cheng (Taxaceae) from China . In: Phytologia . tape 81 , no. 4 , 1996, pp. 322–328 ( page 322ff, scanned from biodiversitylibrary.org [accessed on November 12, 2011]).

↑ Wang Kang, Yang Yong: Taxonomic study on Pseudotaxus (Taxaceae) . In: Acta Phytotaxonomica Sinica . tape 45 , no. 6 , 2007, p. 862-869 ( abstract [accessed November 12, 2011]). doi : 10.1360 / aps07027 (currently unavailable)

Web links

Pseudotaxus. plantsystematics.org, accessed on November 12, 2011 (English, pictures with leaf details).

[FoC-1] ↑ ^a ^b ^c ^d ^e ^f Liguo Fu, Nan Li, Robert R. Mill: Taxaceae. : Pseudotaxus and Pseudotaxus chienii , p. 91 - online with the same text as the printed work , In: Wu Zheng-yi, Peter H. Raven (ed.): Flora of China. Volume 4: Cycadaceae through Fagaceae. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 1999, ISBN 0-915279-70-3 .

[IPCN-2] Pseudotaxus chienii at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis}

[IUCN-3] Pseudotaxus chienii in the IUCN Red List of Threatened Species 2019.1. Listed by: P. Thomas, Y. Yang, 2010. Retrieved May 11, 2019.

[Tropicos-4] Pseudotaxus chienii at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed May 11, 2019.}

[GRIN-5] Pseudotaxus chienii in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved May 11, 2019.}

[Silba-6] John Silba: A new species of Pseudotaxus Cheng (Taxaceae) from China . In: Phytologia . tape 81 , no. 4 , 1996, pp. 322–328 ( page 322ff, scanned from biodiversitylibrary.org [accessed on November 12, 2011]).