Torreya jackii
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Torreya jackii is a mostly shrub-like, rarely growing as a small tree conifer from the genus of the nut slices ( Torreya ). The natural range is in the east of China. The species is classified as critically endangered onthe IUCN Red List and tree populations continue to decline. The wood is used to make agricultural implements and the needles give off a sandalwood- like scentwhen rubbed or burned.
description
Appearance
Torreya jackii grows as an evergreen , up to 12 meter high shrub or small tree with one or more trunks that reach chest height diameters of 20 to rarely 40 centimeters. The trunk bark is gray to dark gray in color and flakes off in thick scales, whereby the pale brown new bark below becomes visible. Sometimes it can also be scared. The branches grow spread out and hanging, they form a narrow, open tree crown. Leafy branches are round, thin, long and flexible. Young shoots are green in the first year and shiny reddish brown in the second.
Buds and needles
The vegetative buds on the ends of the branches are very small. The bud scales of the annual nodes are enlarged, broadly triangular, keeled and shiny brown. They fall off soon after the first year. The needles are usually pendulous and stand at an angle of 20 ° to 60 ° from the branches. They grow on a 1 to 2 millimeter long, twisted stem, are linear to linear-lanceolate, straight or slightly crescent-shaped, but from 2.5 mostly 3.5 to 7 and rarely up to 9 centimeters long and from 2.5 mostly 3 up to 4 millimeters wide. Needles on young twigs can reach a length of up to 23 centimeters. The soft leathery needles suddenly widen towards the base and merge conically into a sharply pointed end in the outer third. The upper side is glossy green and shows an indistinct central rib that lies in a shallow depression at least in the lower half of the needle. On the underside of the needle there are two silver-gray to light brown, 0.5 to 1.4 millimeter wide stomata bands , separated from each other by the 1 to 1.2 millimeter wide, strongly raised, green central rib and from the needle edge by 0.5 to 0.7 millimeters wide green stripes are separated. The edge of the needle is straight or slightly curved downwards. When rubbed, the needles give off a distinct, pleasantly aromatic scent.
Cones and seeds
The pollen cones grow individually in the needle axils. At the base of the cones there are several pairs of bud scales in rows of four. The cones are pale yellow and about 5 to 8 millimeters long with a diameter of 4.5 to 5 millimeters when the pollen is released. The numerous microsporophylls are shield-shaped and carry four or five hanging, small pollen sacs .
The structures containing the seeds grow in pairs in the axils of the needles. They are seated and have two pairs of rounded and keeled cover scales and a small, side cover scales that coat the seed. The ripe aril is smooth, initially whitish frosted or glaucous and when ripe is reddish yellow, obovate, 20 to 30 millimeters long with a diameter of 10 to 12 millimeters. The tip is spiky. The actual seed is smooth or wrinkled.
The seeds ripen in autumn after two years.
Distribution and ecology
The natural range of Torreya jackii is in the east of China in the north of the province Fujian in the counties Taining and Pucheng , in the northeast of Jiangxi and in the south of Zhejiang . The species grows at heights of 400 to 1000 meters as undergrowth in evergreen deciduous forests along rivers, on steep, shady slopes or in secondary forests . The climate ranges from warm-temperate to subtropical and is influenced by the southeast monsoon . The annual rainfall is between 1350 and 1600 millimeters, the mean temperature between 17 and 20 ° C. The minimum temperatures are around −10 ° C, the distribution area is therefore assigned to winter hardiness zone 8 with mean annual minimum temperatures between −12.2 and −6.7 ° C (10 to 20 ° F ). Torreya jackii grows on montane yellow earth soils , on granitic or rhyolite rocky subsoil with a pH value of 4.2 to 5 and sufficient ground or seepage water. The roots have a fleshy bark that can hold water, allowing the species to survive longer periods of drought.
The species is found together with Quercus oxyphylla , Quercus phillyreoides , Quercus glauca , Photinia benthamiana , Loropetalum chinense , Castanopsis eyrei , Schima superba and Rhododendron ovatum . In secondary forests it grows with Loropetalum chinense , Vaccinium bracteatum , Rhododendron ovatum , Symplocos sumuntia and other shrubs.
Hazard and protection
In the Red List of the IUCN is Torreya jackii as endangered ( "Endangered") out. The species grows at significantly lower altitudes than other nut slices and the populations have been greatly reduced in the last 150 years due to the clearing of the forests in order to use the areas for agriculture. There are also few large trees as most have likely been felled. It is believed that stocks have decreased by more than 50 percent. The remaining population is estimated to be around 700,000 not fully grown specimens. Felling of the trees is now banned and there are stocks in protected areas such as Jiangshi Nature Reserve. These measures should slow further decline in the species.
Systematics and Etymology
Torreya jackii is a species from the genus of the nut slices ( Torreya ). It was first described in 1925 by Woonyong Chun as Torreya jackii in the Journal of the Arnold Arboretum . Synonyms of the species are not known. The generic name Torreya is reminiscent of the American botanist and chemist John Torrey (1796–1873), who wrote the two-volume work A Flora of North America together with Asa Gray . The specific epithet jackii honors the Canadian-born American botanist John G. Jack (1861–1949), who taught Woonyong Chun at the Arnold Arboretum .
Of all the nut slices , Torreya jackii has the longest and narrowest needles, which, in contrast to the other species, are also twisted. It also most commonly grows shrubby. Despite these morphological differences, genetic studies show that the species is closely related to Torreya grandis . Torreya jackii is similar to Cephalotaxus fortunei , so the needles are similar and the two species cannot be distinguished by their needles. However, they differ from Torreya jackii by the seated seed cones .
use
The trees are rather small, but the wood is very firm and smells pleasant. It is used to make agricultural implements. The needles give off a very aromatic scent when crushed or burned, reminiscent of the oil of sandalwood . Outside of China, however, the species is rarely cultivated and can only be found in a few botanical and private gardens.
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 998, 1003-1004 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 617-618 .
- 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. 95 (English).
- Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Nikol, Hamburg 2005, ISBN 3-937872-16-7 , p. 649 (reprint from 1996).
Individual evidence
- ↑ a b c d e f g h Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 1003
- ↑ a b c James E. Eckenwalder: Conifers of the World , p. 617
- ^ A b c Liguo Fu, Nan Li, Robert R. Mill: Torreya jackii , in Flora of China , Volume 4, p. 95
- ↑ a b c d James E. Eckenwalder: Conifers of the World , p. 618
- ↑ a b c Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 1004
- ↑ Torreya jackii in the endangered Red List species the IUCN 2013. Posted by: Y. Yang, D. Luscombe, 2010. Retrieved on 31 December 2013.
- ↑ Torreya jackii. In: The International Plant Name Index. Retrieved January 1, 2014 .
- ↑ Torreya jackii. In: The Plant List. Retrieved December 31, 2013 .
- ↑ Exactly: Etymological Dictionary of Botanical Plant Names , p. 649
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 998
- ↑ Christopher J. Earle: Torreya jackii. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed January 5, 2014 (English).
Web links
- Torreya jackii at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed December 31, 2013.
- Torreya jackii in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.