Cephalotaxus hainanensis
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| HL Li |
Cephalotaxus hainanensis is a species fromthe head family (Cephalotaxaceae). It is native to southern China. The species is very similar to Cephalotaxus mannii and is therefore often viewed as a synonym for this species.
description
Cephalotaxus hainanensis grows as an evergreen tree that can reach heights of growth of up to 20 meters and diameters of 0.5 to 1.1 meters at chest height . The light brown to reddish brown trunk bark flakes off. The 8 to 10 centimeters long and 4.5 to 5.5 centimeters thick branches are elliptical to elongated-elliptical in cross-section.
The relatively thin or leathery, straight or slightly sickle-shaped needles are 5 to 7.5 centimeters long and around 3 millimeters wide and linear to linear-lanceolate. They stand on a 0 to 1 millimeter long stem and go from the branches at an angle of 70 to 80 °. The symmetrical base of the needles is blunt to blunt-wedge-shaped, while the tip is prickly. The needle edges are bent back. The upper side of the needle is dark green or shiny olive green in color and on the underside of the needle there are 19 to 26 white to bluish white rows of stomas .
The flowering period of Cephalotaxus hainanensis extends from November to March and the seeds ripen from August to October. The pale yellow, male cones are spherical with a diameter of 4 to 4.5 millimeters and are occasionally on a 1 to 5 millimeter long stem. They are in groups of six to eight and each contain seven to 13 microsporophylls with three to four pollen sacs each . The single, female cones have a 0.6 to 1 centimeter long stalk. They are surrounded by a 2.2 to 3 centimeter long and 1.1 to 1.2 centimeter thick seed coat ( aril ). This is initially green and turns red towards maturity. The obovate to obovate elliptical seeds are 2.2 to 2.8 centimeters long and have a sharply pointed or spiky tip.
The number of chromosomes is 2n = 24.
Distribution and location
The natural range of Cephalotaxus hainanensis comprises five occurrences on the Chinese province of Hainan belonging main island of Hainan . There could also be other deposits in the Chinese provinces of Guangdong and Guangxi .
Cephalotaxus hainanensis thrives at altitudes from 0 to over 1700 meters. The species is found in mountains, where it grows in mixed forests and subtropical rainforests. The stocks on the Chinese mainland could be mixed stocks with Cephalotaxus mannii .
Cephalotaxus hainanensis is classified as "critically endangered" in the IUCN Red List . The destruction of forests to make them usable for tourism is cited as the main risk. In the past, logging played an important role, and more recently the collection of bark and leaves for the production of cephalotaxin and harringtonin for the manufacture of cancer drugs. The declining total population of the species is estimated at around 126,000 trees and covers an area of less than 100 square kilometers on the island of Hainan. The Chinese government has imposed a felling ban to protect the species.
use
The wood of the species was mainly used earlier . The alkaloids cephalotaxine and harringtonine can be extracted from the leaves and the bark, which can be used for the production of cancer drugs.
Systematics
It was first described as Cephalotaxus hainanensis in 1953 by Hui Lin Li in Lloydia , Volume 16 (3), page 164. The species is treated by some authors as a synonym of Cephalotaxus mannii due to the slight morphological differences .
swell
- Christopher J. Earle: Cephalotaxus hainanensis. In: The Gymnosperm Database. conifers.org, November 23, 2012, accessed December 8, 2013 .
- Liguo Fu, Nan Li, Thomas S. Elias & Robert R. Mill: Pinaceae . Picea. In: Wu Zhengyi, Peter H. Raven & Hong Deyuan (eds.): Flora of China . Cycadaceae through Fagaceae. Volume 4. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis 1999, ISBN 0-915279-70-3 , Cephalotaxus hainanensis , pp. 87 ( Cephalotaxus mannii - online - this printed work is online with the same text).
Individual evidence
- ↑ a b c d e f g Christopher J. Earle: Cephalotaxus hainanensis. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed December 8, 2013 .
- ↑ a b c d Christopher J. Earle: Cephalotaxus mannii. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed December 8, 2013 .
- ↑ a b c d Liguo Fu, Nan Li, Thomas S. Elias & Robert R. Mill: Pinaceae . Picea. In: Wu Zhengyi, Peter H. Raven & Hong Deyuan (eds.): Flora of China . Cycadaceae through Fagaceae. Volume 4. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis 1999, ISBN 0-915279-70-3 , Cephalotaxus mannii , pp. 87 ( Cephalotaxus mannii - online - this printed work is online with the same text).
- ↑ a b c d Cephalotaxus hainanensis in the endangered Red List species the IUCN 2013. Posted by: Y. Yang, W. Liao, 2010. Retrieved on December 8, 2013.
- ↑ Cephalotaxus hainanensis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed December 8, 2013.
- ↑ Cephalotaxus hainanensis. In: The Plant List. www.theplantlist.org, accessed December 8, 2013 .