Chestnut презентация

Chestnut

The chestnuts are a group of eight or nine species of deciduous trees and shrubs in the genus Castanea, in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere.
The name also refers to the edible nuts they produce.
Chestnut trees are of moderate growth rate (for the Chinese chestnut tree) to fast-growing for American and European species. Their mature heights vary from the smallest species of chinkapins, often shrubby, to the giant of past American forests, C. dentata that could reach 60 m. Between these extremes are found the Japanese chestnut at 10 m average; followed by the Chinese chestnut at about 15 m, then the European chestnut around 30 m.
The Chinese and more so the Japanese chestnuts are both often multileadered and wide-spreading, whereas European and especially American species tend to grow very erect when planted among others, with little tapering of their columnar trunks, which are firmly set and massive. When standing on their own, they spread on the sides and develop broad, rounded, dense crowns at maturity. The latter two's foliage has striking yellow autumn coloring.

Its bark is smooth when young, of a vinous maroon or red-brown color for the American chestnut, grey for the European chestnut. With age, American species' bark becomes grey and darker, thick, and deeply furrowed; the furrows run longitudinally, and tend to twist around the trunk as the tree ages; it sometimes reminds one of a large cable with twisted strands.
The leaves are simple, ovate or lanceolate, 10–30 cm long and 4–10 cm wide, with sharply pointed, widely spaced teeth, with shallow rounded sinuates between.
The flowers follow the leaves, appearing in late spring or early summer or into July. They are arranged in long catkins of two kinds, with both kinds being borne on every tree. Some catkins are made of only male flowers, which mature first. Each flower has eight stamens, or 10 to 12 for C. mollissima. The ripe pollen carries a heavy, sweet odorthat some people find too sweet or unpleasant. Other catkins have these pollen-bearing flowers, but also carry near the twig from which these spring, small clusters of female or fruit-producing flowers. Two or three flowers together form a four-lobed prickly calybium, which ultimately grows completely together to make the brown hull, or husk, covering the fruits.

Chestnut flowers are not self-compatible, so two trees are required for pollination. All Castanea species readily hybridize with each other.
The fruit is contained in a spiny (very sharp) cupule 5–11 cm in diameter, also called "bur" or "burr". The burrs are often paired or clustered on the branch and contain one to seven nuts according to the different species, varieties, and cultivars. Around the time the fruits reach maturity, the burrs turn yellow-brown and split open in two or four sections. They can remain on the tree longer than they hold the fruit, but more often achieve complete opening and release the fruits only after having fallen on the ground; opening is partly due to soil humidity.
The chestnut fruit has a pointed end with a small tuft at its tip (called "flame" in Italian), and at the other end, a hilum – a pale brown attachment scar. In many varieties, the fruit is flattened on one or two sides. It has two skins. The first one is a hard, shiny, brown outer hull or husk, called the pericarpus; the industry calls this the "peel". Underneath the pericarpus is another, thinner skin, called the pellicle or episperm. The pellicle closely adheres to the seed itself, following the grooves usually present at the surface of the fruit. These grooves are of variable sizes and depths according to the species and variety.
The fruit inside these shows two cotyledons with a creamy-white flesh throughout, except in some varieties which show only one cotyledon, and whose episperm is only slightly or not intruded at all.

Usually, these varieties have only one large fruit per burr, well rounded (no flat face) and which is called "marron" (marron de Lyon in France, marron di Mugello in Italy, or paragon).
Chestnut fruit has no epigeal dormancy and germinate right upon falling to the ground in the autumn, with the roots emerging from the seed right away and the leaves and stem the following spring. Because the seeds lack a coating or internal food supply, they lose viability soon after ripening and must be planted immediately.
The superior fruiting varieties among European chestnuts have good size, sweet taste, and easy-to-remove inner skins. American chestnuts are usually very small (around 5 g), but sweet-tasting with easy-to-remove pellicles. Some Japanese varieties have very large nuts (around 40 g), with typically difficult-to-remove pellicles. Chinese chestnut pellicles are usually easy to remove, and their sizes vary greatly according to the varieties, although usually smaller than the Japanese chestnut.

American chestnut

The American chestnut is a large deciduous tree of the beech family native to eastern North America. The American chestnut was one of the most important forest trees throughout its range and was considered the finest chestnut tree in the world.
However, the species was devastated by chestnut blight, a fungal disease that came from chestnut trees introduced from East Asia. It is estimated that between 3 and 4 billion American chestnut trees were destroyed in the first half of the 20th century by blight after its initial discovery in 1904. Very few mature specimens of the tree exist within its historical range, although many small shoots of the former live trees remain. There are hundreds of large American chestnuts outside its historical range, some in areas where less virulent strains of the pathogen are more common, such as the 600 to 800 large trees in Northern Michigan. The species is listed as endangered in the United States and Canada.
Chinese chestnut trees have been found to have the highest resistance/immunity to chestnut blight, therefore there are currently programs to revive the American chestnut tree population by cross-breeding the blight-resistant Chinese chestnut with the American chestnut tree, so that the blight-resistant genes from Chinese chestnut may protect and restore the American chestnut population back to its original status as a dominant species in American forests.

Castanea dentata is a rapidly-growing deciduous hardwood tree, historically reaching up to 30 metres in height, and 3 metres in diameter. It ranged from Maine and southern Ontario to Mississippi, and from the Atlantic coast to the Appalachian Mountains and the Ohio Valley. C. dentata was once one of the most common trees in the Northeastern United States. In Pennsylvania alone, it is estimated to have comprised 25–30% of all hardwoods. The tree's huge population was due to a combination of rapid growth and a large annual seed crop in comparison to oaks which do not reliably produce sizable numbers of acorns every year. Nut production begins when C. dentata is 7–8 years old.
There are several similar chestnut species, such as the European sweet chestnut, Chinese chestnut, and Japanese chestnut. The American species can be distinguished by a few morphological traits, such as leaf shape, petiole length and nut size. For example, it has larger and more widely spaced saw-teeth on the edges of its leaves, as indicated by the scientific name dentata, Latin for "toothed". According to a 1999 study by American Society for Horticultural Science, the Ozark chinkapin, which is typically considered either a distinct species or a subspecies of the Allegheny chinkapin may be ancestral to both the American chestnut and the Allegheny chinkapin. A natural hybrid of Castanea dentata and Castanea pumila has been named Castanea neglecta.

The leaves, which are 14–20 cm long and 7–10 cm broad, also tend to average slightly shorter and broader than those of the sweet chestnut. The blight-resistant Chinese chestnut is now the most commonly planted chestnut species in the US, while the European chestnut is the source of commercial nuts in recent decades. It can be distinguished from the American chestnut by its hairy twig tips which are in contrast to the hairless twigs of the American chestnut. The chestnuts are in the beech family along with beech and oak, but are not closely related to the horse-chestnut, which is in the family Sapindaceae.
The chestnut is monoecious, producing many small, pale green (nearly white) male flowers found tightly occurring along 6 to 8 inch long catkins. The female parts are found near base of the catkins (near twig) and appear in late spring to early summer. Like all members of the family Fagaceae, American chestnut is self-incompatible and requires two trees for pollination, which can be any member of the Castanea genus.
The American chestnut is a prolific bearer of nuts, usually with three nuts enclosed in each spiny, green burr, and lined in tan velvet. The nuts develop through late summer, with the burrs opening and falling to the ground near the first fall frost.
The American chestnut was a very important tree for wildlife, providing much of the fall mast for species such as white-tailed deer and wild turkey and, formerly, the passenger pigeon. Black bears were also known to eat the nuts to fatten up for the winter.

Dwarf chestnut

Castanea pumila, commonly known as the Allegheny chinquapin, American chinquapin (from the Powhatan) or dwarf chestnut, is a species of chestnut native to the southeastern United States. The native range is from Maryland and extreme southern New Jersey and southeast Pennsylvania south to central Florida, west to eastern Texas, and north to southern Missouri and Kentucky. The plant's habitat is dry sandy and rocky uplands and ridges mixed with oak and hickory to 1000 m elevation. It grows best on well-drained soils in full sun or partial shade.
It is a spreading shrub or small tree, reaching 2–8 m in height at maturity. The bark is red- or gray-brown and slightly furrowed into scaly plates. The leaves are simple, narrowly elliptical or lanceolate, yellow-green above and paler and finely hairy on the underside. Each leaf is 7.5–15 cm long by 3–5 cm wide with parallel side veins ending in short pointed teeth. The flowers are monoecious and appear in early summer. Male flowers are small and pale yellow to white, borne on erect catkins 10–15 cm long attached to the base of each leaf. Female flowers are 3 mm long and are located at the base of some catkins. The fruit is a golden-colored cupule 2–3 cm in diameter with many sharp spines, maturing in autumn. Each cupule contains one ovoid shiny dark brown nut that is edible.
A natural hybrid of Castanea pumila and Castanea dentata has been named Castanea neglecta.

Allegheny chinquapin occurs in mixed hardwood forests among pine and oak trees on high ridges and slopes that are free from limestone. It grows on black sandy dunes in the Carolinas, but not on frontal dunes. It is also found on well-drained stream terraces, dry pinelands, and disturbed sites such as railroad rights- of-way, power line clearings, fence and hedgerows, pine plantations, and old fields. Allegheny chinquapin is closely related to the American chestnut, Castanea dentata, and both trees can be found in the same habitat. Allegheny chinquapin can be distinguished by its smaller nut (half the size of a chestnut) that is not flattened (chestnuts are flattened on one side). The leaves of the Allegheny chinquapin are smaller than the American chestnut and have less distinct teeth. Allegheny chinquapin, however, is less susceptible to the chestnut blight fungus that devastated the American chestnut. While the chinquapin does blight to some degree, it continues to send out suckers that will produce fruit. Chinquapins are quite vulnerable nevertheless, and there are many reports of heavily diseased and cankered trees.

Chinese chestnut

Castanea mollissima, also known as the Chinese chestnut, is a member of the family Fagaceae, and a species of chestnut native to China, Taiwan, and Korea.
It is a deciduous tree growing to 20 m tall with a broad crown. The leaves are alternate, simple, 10–22 cm long and 4.5–8 cm broad, with a toothed margin. The flowers are produced in catkins 4–20 cm long, with the female flowers at the base of the catkin and males on the rest. The fruit is a densely spiny cupule 4–8 cm diameter, containing two or three glossy brown nuts; these are 2–3 cm diameter on wild trees. The scientific name mollissima derives from the softly downy shoots and young leaves.
Chinese chestnut has been cultivated in East Asia for millennia and its exact original range cannot be determined. In the provinces of Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Liaoning, Nei Mongol, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xizang, Yunnan, and Zhejiang, and also to Taiwan and Korea. It grows close to sea level in the north of its range, and at altitudes of up to 2,800 m in the south of the range. The species prefers full sun and acidic, loamy soil, and has a medium growth rate.

Chinese chinkapin

Castanea henryi, Henry chestnut, Henry's chestnut, or Chinese chinquapin (a name it shares with Castanea seguinii), pearl chestnut is a species of chestnut native to south-central and southeast China. A tree reaching 30 m, it is a source of good timber, but has smaller nuts than its size might suggest. Like its close relative Castanea mollissima (Chinese chestnut) it is widely cultivated in China, and quite a few varieties have been developed in recent times.

Seguin's chestnut

Castanea seguinii, called Seguin chestnut, Seguin's chestnut, or Chinese chinquapin (a name it shares with Castanea henryi) is a species of chestnut native to south‑central and southeast China.
Castanea seguinii are small trees or shrubs, rarely reaching 12 m. Their stipules are narrowly lanceolate, 0.7 to 1.5 cm long, and are shed (become deciduous) when the plant is in fruit. Leaf petioles are 0.5 to 1.5 cm long. Leaves are 6 to 14 cm long, with their abaxial sides covered with yellowish‑brown to gray scaly glands, and have sparse hairs along the veins when young. Leaf blades are oblong‑obovate to elliptic‑oblong in shape, with bases rounded or infrequently subcordate, but cuneate when young, with acuminate apices. Leaf margins are coarsely serrate. Male inflorescences are 5 to 12 cm long and catkin‑like. Female inflorescences are held in a cupule, with one to two (rarely more) flowers in each. Cupules are 3 to 5 cm wide, and covered with sparsely pilose spiny bracts which are 6 to 10 mm long. Each cupule produces two or three nuts, rarely more, with each nut being 1.5 to 2.0 cm in diameter.

Korean chestnut

Castanea crenata, known as Korean chestnut, Korean castanea, and Japanese chestnut, is a species of chestnut native to Japan and Korea. Castanea crenata exhibits resistance to Phytophthora cinnamomi, the fungal pathogen that causes ink disease in several Castanea species. The mechanism of resistance of Castanea crenata to Phytophthora cinnamomi may derive from its expression of the Cast_Gnk2-like gene.
Castanea crenata is a small to medium-sized deciduous tree growing to 10–15 m tall. The leaves are similar to those of the sweet chestnut, though usually a little smaller, 8–19 cm long and 3–5 cm broad. The flowers of both sexes are borne in 7–20 cm long, upright catkins, the male flowers in the upper part and female flowers in the lower part. They appear in summer, and by autumn, the female flowers develop into spiny cupules containing 3–7 brownish nuts that are shed during October.

Sweet chestnut