Torreya jackii
Torreya jackii is usually shrubby, rarer than small tree growing conifers from the kind of nut yew ( Torreya ). The natural range is in the east of China. The species is classified as endangered in the IUCN Red List and the stocks go through the felling of trees continues to back. The wood is used for the manufacture of agricultural equipment and the needles spread when bruised or burning a hint of sandalwood scent.
- 6.1 Literature
- 6.2 Notes and references
Description
Appearance
Torreya jackii grows as evergreen, up to 12 meters tall shrub or small tree with one or more strains, the diameter at breast height of 20 to 40 centimeters rarely achieve. The Stammborke is colored gray to dark gray and peeling off in thick scales, revealing the underlying pale brown, new bark is visible. Sometimes it can also be furrowed. The branches grow spread and hanging, they form a narrow, open canopy. Leafy branches are terete, thin, long and flexible. Young shoots are in the first year green and brown shiny reddish in the second.
Buds and needles
The vegetative buds on the ends of the branches are very small. The bud scales the one-year nodes are enlarged, broadly triangular, keeled and shiny brown. They fall soon after the first year. The needles are usually contiguous and are at an angle of 20 ° to 60 ° from the branches off. They grow at a 1 to 2 millimeters long, twisted stalk, are linear to linear - lanceolate, straight or slightly curved sickle-shaped, but usually from 2.5 3.5 to 7 and rarely up to 9 inches long and from 2.5 usually 3 to 4 mm wide. Needles on young branches can reach a length of up to 23 centimeters. The soft leathery needles suddenly widen towards the base, and go in the outer third tapered into a sharp pointed end on. The top is glossy green and shows a vaguely educated middle rib, which is at least in the lower half of the needle in a shallow depression. On the needle base, there are two silver-gray to light brown, 0.5 to 1.4 millimeters wide stomatal bands separated from each other by 1 to 1.2 millimeters wide, highly elevated, green midrib and the needle edge by 0.5 to 0.7 millimeters wide green stripes are separated. The needle edge is straight or slightly bent downward. The needles spread when rubbed a clear, pleasant and aromatic fragrance.
Cones and seeds
The pollen cones grow individually in the needle shoulders. At the base of the pins are in rows of four more pairs of bud scales. The cones are pale yellow, and in the output of pollen about 5 to 8 mm long with a diameter 4.5 to 5 millimeters. The numerous Mikrosporophylle are shield-shaped and wear four or five hanging, small pollen sacs.
The seeds containing structures grow in pairs in the axils of the needles. You are sitting and have two pairs of rounded and keeled bracts and a small lateral Deckschuppe, coats the seeds. The mature aril is smooth, at first frosted whitish or reddish yellow when ripe and Glauk, obovate, 20-30 mm long with diameters of 10 to 12 millimeters. The tip is mucronate. The actual seed is smooth or wrinkled.
The seeds mature after two years in the fall.
Distribution and ecology
The natural range of Torreya jackii lies in the east of China in the north of Fujian province in the circles Taining and Pucheng, in northeastern Jiangxi and southern Zhejiang. It grows at altitudes 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 1350-1600 mm, the mean temperature between 17 ° and 20 ° Celsius. The minimum temperatures are -10 ° C, the area of distribution is thus the Hardiness Zone 8 attributed with mean annual minimum temperatures between -12.2 to -6.7 ° C (10 ° to 20 ° Fahrenheit ). Torreya jackii growing on montane yellow earth soils on granitic or rhyolitic bedrock with a pH value of 4.2 to 5 and sufficient reason or leachate. The roots have a fleshy bark which can store water and thus enables the species to survive long dry periods.
One finds the kind ovatum together with Quercus oxyphylla, Quercus phillyreoides, Quercus glauca, Photinia benthamiana, Loropetalum chinense, eyrei Castanopsis, Schima superba and rhododendron. In secondary forests it grows with Loropetalum chinense, Vaccinium bracteatum, Rhododendron ovatum, Symplocos sumuntia and other shrubs.
Threats and conservation
In the IUCN Red List Torreya jackii is listed as endangered ( " Endangered "). The species grows in much lower altitudes than other nut yews and the stocks have been greatly reduced over the past 150 years by cutting down the forests to use the areas for agriculture. There are also a few large trees, as most were probably like. It is believed that the stocks have been reduced by more than 50 percent. The remaining population is estimated at around 700,000 not fully grown specimens. Meanwhile, the felling of trees is prohibited and there are stocks in protected areas such as the Jiangshi nature reserve. These measures should slow down the further decline of the species.
Systematics and etymology
Torreya jackii is a species in the genus of yew nut ( Torreya ). It was 1925 by Woonyong Chun as Torreya jackii the Journal of the Arnold Arboretum firstdescribed. Synonyms of species are not known. The genus name Torreya reminiscent of the American botanist and chemist John Torrey (1796-1873), who wrote the two-volume work A Flora of North America, along with Asa Gray. The specific epithet honors the jackii in Canada -born, American botanist John G. Jack (1861-1949), the Woonyong Chun has taught at the Arnold Arboretum.
Torreya jackii has all of the longest and narrowest nut yew needles that are also twisted in contrast to the other species. It also grows most commonly Shrubby. Despite these morphological differences are genetic studies indicate that the species is closely related to Torreya grandis. Torreya, Cephalotaxus fortunei jackii similar, then the same needles and the two species can not be distinguished by their needles. However, they differ in the seated seed cones of Torreya jackii.
Use
The trees are rather small, but the wood is very firm and has a pleasant smell. It is used for the preparation of agricultural equipment. The needles spread a very aromatic scent when crushed or burned, reminiscent of the oil of sandalwood. Outside China, the species is hardly cultivated and is found only in a few botanical and private gardens.