Primeval sequoia

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Primeval sequoia
Primeval sequoia

Primeval sequoia

Systematics
Class : Coniferopsida
Order : Conifers (Coniferales)
Family : Cypress family (Cupressaceae)
Subfamily : Sequoioideae
Genre : Metasequoia
Type : Primeval sequoia
Scientific name
Metasequoia glyptostroboides
Hu & Cheng
bark
Long shoot with short shoots
Short shoots with needles in autumn colors
Short shoots with male cones in October
Male cones
Ripe cones with seeds
Tree grate (25 years)

The primeval sequoia ( Metasequoia glyptostroboides ), also called Chinese redwood , metasequoie or water fir, is considered a living fossil . It was only discovered in 1941 in an inaccessible mountain region in the Sichuan and Hubei regions of the People's Republic of China and was previously only known from fossil finds. It is the only recent species in the genus Metasequoia .

description

Habitus

The deciduous primeval sequoia grows to heights of 30 to 35 m, in individual cases more than 50 m and a diameter of 1 to 2.2 m at breast height . The base of the straight trunk is significantly widened. Young trees have a pyramidal crown , while old trees are broad and rounded. The branches of the first order are irregularly shaped and mostly spread out. Branches of a higher order are arranged hanging down and facing each other. Both short and long shoots are formed. The short shoots fall off together with the needles in autumn. Freestanding trees are branched to the ground and have distinctive, deep trunks. The maximum age is given as 420 years.

The seedlings have two seed leaves ( cotyledons ).

root

The primeval sequoia usually forms a relatively flat, far-reaching root system, which can extend beyond the projection of the crown surface . The lateral roots grow first as shallow horizontal roots, which only later grow downwards and reach depths of 50 to 100 centimeters.

bark

The bark of the branches is initially green, but turns gray to gray-brown in the second and third years. The trunk of young trees has a reddish brown bark that flakes off in thin sheets. The trunks of older trees have a gray to gray-brown bark that peels off in long strips, exposing the red-brown inner bark underneath.

Wood

The light sapwood differs in color from the red-brown heartwood . The soft wood is light, easy to work with and easily takes on color. The straight wood fibers are relatively coarse. The density with a wood moisture content of 15% is between 0.29 and 0.38 g / cm³.

Technical characteristics value unit
Flexural strength 480 kg / cm²
Compressive strength 258 kg / cm²
tensile strenght 457 kg / cm²
Late wood percentage 12.5

Buds and needles

The ovoid-elliptical and blunt winter buds are bare and are around 4 mm long and 3 mm wide. The hood-like bud scales are yellowish-brown in color.

The flat needles are already fully developed in May and become 0.8 to 3.5 cm long and 1 to 2.5 mm wide. They are blue-green on the top and light green on the underside. There are two yellowish stomatal bands on the underside of the needle . Each needle has three resin channels. The needles are spiraled on long shoots and parted on short shoots and are largely arranged opposite one another . This feature allows it to be reliably distinguished from the bald cypress , which looks similar from a distance and has alternate foliage. The autumn color begins with a delicate pink-yellow in October and changes to salmon red to copper brown in November. The needles fall off together with the short shoots.

Flowers, cones and seeds

The primeval sequoia is monoecious ( monoecious ). He becomes manable at the age of 25 to 30 . The flowering time in the natural range lasts from February to March, depending on the location. The kitten-like male pollen cones are 5 to 10 cm long and are located in the leaf axils of last year's long shoots. The female cones develop at the end of short shoots. They stand upright at flowering time, are only about 9 mm long and form pollination droplets with which they catch the pollen from the air. The cones are spherical to ovate when ripe and stand on a 2 to 4 cm long stem. They are around 1.8 to 2.5 cm long and 1.6 to 2.3 cm wide. Each tenon consists of 11 to 12 opposing pairs of wedge-shaped tenon scales. They are initially green and turn brown as they mature. The cones ripen in November to December of the flowering year. Each cone scale bears 5 to 9 flat and winged seeds in a row.

The seeds are obovate, winged all around and have a notched apex . They become about 5 mm long. The thousand grain weight is between 1.75 and 2.3 g.

Chromosome number

The primeval sequoia has a chromosome number of 2n = 22.

Distribution and location

The primeval sequoia only occurs naturally in small relic populations in the Shizhu District in eastern Sichuan , in the Lichuan District in western Hubei, and in the Longshan District and Sangzhi District in northwestern Hunan in China . Since its discovery it has been planted as an ornamental tree in parks and gardens around the world .

The primeval sequoia is a fast-growing tree species of the warm-humid climate and grows in species-rich mixed forests in moist, non-shady mountain areas at altitudes between 750 and 1500 m above sea level. NN. It grows on permeable, deep, nutrient - and humus - rich loam soils . The primeval sequoia is frost hardy down to −32 ° C , but is sensitive to late frosts. Although abundant rainfall promotes growth, it also grows in locations with annual rainfall of 400 to 450 mm. It does not tolerate waterlogging. In the natural range, the species is mainly found on river and stream banks and in damp gorges. It colonizes slightly acidic to neutral sandstone weathered soils.

Diseases and pests

Primeval sequoia seedlings are susceptible to pathogens of the species Rhizoctonia and Pythium , which cause falling-over disease . Anthracnose germs can play a certain economic role. The species Cryptothelea variegata , Cryptothelea minuscula and Holotrichia diomphalia are named among leaf-eating pests . Anoplophora chinensis and Anoplophora glabripennis are wood and root-dwelling pests that can cause total failures. Trees that are heavily shaded die or suffer severe growth losses.

Systematics

In 1941 the genus Metasequoia was separated from the genus Sequoia . Ten species of this genus are known from the Cretaceous period . They were spread over large parts of the northern hemisphere. Of these species, only the primeval sequoia survived. It was in 1948 by hu xiansu (1894-1968) and Cheng Wan-Chun (1908-1987) and Metasequoia glyptostroboides first described . It is considered extremely unlikely that the genus Sequoia evolved from the genus Metasequoia .

swell

Individual evidence

  1. ↑ Schütt, Weisgerber, Schuck, Lang, Stimm, Roloff: Lexicon of conifers . Nikol, Hamburg 2008, ISBN 3-933203-80-5 , p. 259 .
  2. ↑ Armin Jagel, Veit Martin Dörken: The cones of the cypress family (Cupressaceae) - Part 1: Subfamilies Cunninghamioideae, Athrotaxoideae, Taiwanioideae, Sequoioideae, Taxodioideae. Communications from the German Dendrological Society, Vol. 100, 2015, pp. 161–176.
  3. ^ Tropicos. [1]

Web links

Commons : Ancient sequoia tree ( Metasequoia glyptostroboides )  - Collection of images, videos and audio files