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Celtis

Celtis

Celtis

 

Celtis is a genus of about 60–70 species of deciduous trees, commonly known as hackberries or nettle trees, widespread in warm temperate regions of the Northern Hemisphere, in southern Europe, southern and eastern Asia, and southern and central North America, south to central Africa, and northern and central South America. The genus is present in the fossil record at least since the Miocene of Europe, and Paleocene of North America and eastern Asia. Celtis is a genus of about 60–70 species of deciduous trees, commonly known as hackberries or nettle trees, widespread in warm

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Celtis is a genus of about 60–70 species of deciduous trees, commonly known as hackberries or nettle trees, widespread in warm temperate regions of the Northern Hemisphere, in southern Europe, southern and eastern Asia, and southern and central North America, south to central Africa, and northern and central South America. The genus is present in the fossil record at least since the Miocene of Europe, and Paleocene of North America and eastern Asia.Several species are grown as ornamental trees, valued for their drought tolerance. They are a regular feature of arboreta and botanical gardens, particularly in North America. Chinese hackberry (C. sinensis) is suited for bonsai culture, while a magnificent specimen in Daegu-myeon is one of the natural monuments of South Korea. Some, including common hackberry (C. occidentalis) and C. brasiliensis, are honey plants and pollen source for honeybees of lesser importance. C. occidentalis was used by the Omaha, eaten casually, as well as the Dakota people, who pounded them fine, seeds and all. The Pawnee used the pounded fruits in combination with fat and parched corn.Trees or shrubs with smooth grey bark. Leaves simple, alternate, petiolate, 3-nerved with unequal bases. Stipules narrow linear, caducous. Flowers unisexual, bisexual or polygamous in axillary or lateral clusters on branches of current season. Male flowers: in axillary or lateral cymes, fertile flowers solitary. Perianth 4 or 5, imbricate, deciduous. Stamens 4-5, filaments short, erect, surrounding a hairy disc. Ovary sessile on a hairy disc, style central, 2-fid, plumose. Fruit a small ovoid or globose drupe, endocarp hard and stony, smooth or rugose. Trees or rarely shrubs , to 30 m; crowns spreading. Bark usually gray, smooth or often fissured and conspicuously warty. Branches without or with thorns, slender, glabrous or pubescent. Leaves: stipules falling early. Leaf blade deltate to ovate to oblong-lanceolate, base oblique or cuneate to rounded, margins entire or serrate-dentate; venation 3(-5)-pinnate. Inflorescences: staminate inflorescences cymes or fascicles; pistillate solitary or few-flowered clusters. Flowers usually unisexual, staminate and pistillate on same plants, along with a few bisexual flowers, pedicellate on branches of current year, appearing in mid or late spring. Staminate flowers: filaments incurved in bud, exserted after anthesis; gynoecium minute, rudimentary. Pistillate flowers: calyx slightly to deeply 4(-5)-lobed; stamens 4-5, inserted on pilose receptacle, included, often nonfunctional filaments usually shorter than in staminate flowers, rarely absent; anthers ovate, face to face in bud, extrorse; ovaries sessile, ovoid, 1-locular; styles short, sessile, divided into 2 divergent, elongate, reflexed lobes, lobes entire or 2-cleft. Fruits fleshy drupes, ovoid or globose; outer mesocarp thick, firm, inner mesocarp thin, fleshy; stones thick walled, ripening in autumn, persisting after leaves fall. x = 10.The European nettle tree (Celtis australis), also known as Mediterranean hackberry, lote tree, or honeyberry, is a large deciduous tree from Europe, North Africa, and Asia Minor. It can grow up to 25 m high in warm climates, though in cooler sites it rarely reaches that height. Celtis australis can usually be found in mixed deciduous forests with oaks, hornbeams, ashes and maples. It prefers poor soils made of sand, rock or clay and is drought tolerant. This species prefers full-sun exposure and suffers in severe winter frosts. The nettle tree is mainly used for afforestation of difficult terrains and erosion control, and in urban environments because it tolerates city air pollution.

 

A seldom used tree with a round to umbel-shaped crown. Mature specimen may attain a height of over 20 m, the tree grows with gracefully hanging branches. The bark is grey and smooth, when maturing peeling in small plates. The ovate-lanceolate to ovoid leaf is sharply toothed and with a very long twisted point. The topside is dark green, the underside is grey green. The leaf is rough to the touch on both sides. After an inconspicuous inflorescence the berry-like stone fruits appear. They are dark red to almost black and taste sweet. They hang down from circa 2 cm long, pilose stalks. The wood is useful and the young, flexible twigs were once used for whips, hence its name “whip tree”. A graceful tree that is little susceptible to air pollution. Young twigs can be damaged by frosts.Common hackberry is somewhat drought tolerant [52]. After a study of trees in Nebraska and Kansas before and after the severe drought of the 1930s, researchers reported that common hackberry "endured drought especially well". In ravines in Kansas, common hackberry growth averaged 0.6 inch (17 mm) in a wet year and 0.5 inch (12 mm) in a dry year. Growth rate differences were greater in dry than mesic ravines [9]. In southeastern South Dakota, 96% of common hackberry trees remained alive through the 1934 to 1939 survey period, which included 2 years of above-average drought intensity [129]. However, after studies at North Dakota's Mandan Experimental Station, common hackberry was not recommended for Northern Great Plains sites without favorable moisture [65]. Tolerance of excessive soil moisture or flooding likely increases with common hackberry age. Seedlings are much more sensitive to saturation than trees (review [107]). In the Trelease Woods of east-central Illinois, common hackberry trees occurred in all soil types but dominated in Humic Gley soils with standing water at or above the soil surface throughout the spring. Sapling densities were lowest in Humic Gley soils and highest in Brunizem soils that were saturated until late spring. Seedling densities were lowest in Humic Gley soils and highest in Transitional soils with maximum drainage and a water table below the solum all spring and summer [63]. Along the Wabash and/or Tippecanoe rivers in Indiana, common hackberry seedlings and saplings were killed by submergence during high flood levels in June [117]. In the greenhouse, first-year common hackberry seedlings survived 60 days in saturated soils. Saturated seedlings were shorter than control seedlings, although not significantly. A few seedlings died when removed from saturated conditions [87]. In central Illinois, common hackberry saplings and seedlings were more than twice as abundant in wet-mesic than dry-mesic, mesic, or wet sites [5].In general, common hackberry trees are more common in upper, less frequently flooded sites than lower, frequently flooded sites. Along the lower Chippewa River in northwestern Wisconsin, common hackberry was most common on river terraces and floodplain forests that were 13 feet (4 m) or more above river level [13]. In streamside forests in the Sangamon River Basin of Illinois, common hackberry was a dominant species in areas between sites receiving substantial flooding and sites receiving almost no flooding (flooding frequency 0%-3%) [19]. In streamside forests in Piatt County, Illinois, common hackberry dominated sites that were flooded 1.5% to 3% of a 55-year time period and was present, but much less common, in areas flooded for 18% of the same time period [18]. In secondary forests along the Raritan River of New Jersey, common hackberry occurred in high (>11 feet (3.4 m)) but not low floodplain sites. High sites had sandy loam soils and were flooded less than 1 day each year. Low sites had predominantly clay loam soils and were flooded 0.7 to 18 days per year [61]. After surveying ranchers and farmers in North Dakota and Montana, researchers found that those who planted common hackberry on sites with a shallow water table ranked its windbreak performance lower than those who planted it on sites with deeper water tables [192]. (Source: www.fs.fed.us)

 

 

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