The genus Quercus contains about 500 known species, plus about 180 hybrids between them. The genus, as is the case with many large genera , is divided into subgenera and sections . Traditionally, the genus Quercus was divided into the two subgenera Cyclobalanopsis , the ring-cupped oaks, and Quercus , which included all the other sections. However, a comprehensive revision in 2017 identified different relationships. Now the genus is commonly divided into a subgenus Quercus and a subgenus Cerris , with Cyclobalanopsis included in the latter. The sections of subgenus Quercus are mostly native to the New World , with the notable exception of the white oaks of sect. Quercus and the endemic Quercus pontica . In contrast, the sections of the subgenus Cerris are exclusively native to the Old World .
41-574: See also List of Quercus species . An oak is a hardwood tree or shrub in the genus Quercus of the beech family . They have spirally arranged leaves, often with lobed edges, and a nut called an acorn , borne within a cup. The genus is widely distributed in the Northern Hemisphere; it includes some 500 species, both deciduous and evergreen . Fossil oaks date back to the Middle Eocene . Molecular phylogeny shows that
82-534: A food additive and consequently does not hold an E number . Under directive 89/107/EEC, tannic acid can be referred to as a food ingredient. The E-number E181 is sometimes incorrectly used to refer to tannic acid; this in fact refers to the INS number assigned to tannic acid under the FAO-WHO Codex Alimentarius system. In conjunction with magnesium and sometimes activated charcoal, tannic acid
123-630: A narrow belt along the Himalayas to cover mainland and island Southeast Asia as far as Sumatra , Java , Borneo , and Palawan . Finally, oaks of multiple sections ( Cyclobalanopsis , Ilex , Cerris , Quercus and related genera like Lithocarpus and Castanopsis ) extend across east Asia including China, Korea, and Japan. Potential records of Quercus have been reported from Late Cretaceous deposits in North America and East Asia. These are not considered definitive, as macrofossils older than
164-485: A range of flavours, colours, and aromas. The spongy bark of the cork oak is used to make traditional wine bottle corks. Almost a third of oak species are threatened with extinction due to climate change, invasive pests , and habitat loss . In culture, the oak tree is a symbol of strength and serves as the national tree of many countries. In Indo-European and related religions, the oak is associated with thunder gods . Individual oak trees of cultural significance include
205-504: A single oak tree produces both staminate ('male') flowers in the form of catkins , and small pistillate ('female') flowers, meaning that the trees are monoecious . The fruit is a nut called an acorn , borne in a cup-like structure known as a cupule ; each acorn usually contains one seed and takes 6–18 months to mature, depending on the species. The acorns and leaves contain tannic acid , which helps to guard against fungi and insects. There are some 500 extant species of oaks. Trees in
246-553: A small area of the west of Cuba ; in Mesoamerica it occurs mainly above 1000 metres. The genus crossed the isthmus of Panama when the northern and southern continents came together and is present as one species, Q. humboldtii , above 1000 metres in Colombia. The oaks of North America are of many sections ( Protobalanus , Lobatae , Ponticae , Quercus , and Virentes ) along with related genera such as Notholithocarpus . In
287-462: Is a specific form of tannin , a type of polyphenol . Its weak acidity ( pK a around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C 76 H 52 O 46 , which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on
328-462: Is also an alternative for fluorocarbon aftertreatments to impart anti-staining properties to polyamide yarn or carpets. However, due to economic considerations currently the only widespread use as textile auxiliary is the use as an agent to improve chlorine fastness, i.e. resistance against dye bleaching due to cleaning with hypochlorite solutions in high-end polyamide 6,6-based carpets and swimwear. It is, however, used in relatively small quantities for
369-627: Is also found in commercially available iron/steel corrosion treatments , such as Hammerite Kurust. In many parts of the world, its uses in food are permitted. In the United States , tannic acid is generally recognized as safe by the Food and Drug Administration for use in baked goods and baking mixes, alcoholic and non-alcoholic beverages, frozen dairy products, soft and hard candy, meat products, and rendered animal fat. According to EU directive 89/107/EEC, tannic acid cannot be considered as
410-460: Is called gallotannic acid and is found in oak galls. The quercitannic acid molecule is also present in quercitron , a yellow dye obtained from the bark of the Eastern black oak ( Quercus velutina ), a forest tree indigenous in North America. It is described as a yellowish-brown amorphous powder. In 1838, Jöns Jacob Berzelius wrote that quercitannate is used to dissolve morphine. In 1865 in
451-482: Is found in the seeds , bark , cones , and heartwood . Tannic acid is a common mordant used in the dyeing process for cellulose fibers such as cotton , often combined with alum and/or iron . The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex. However this use has lost considerable interest. Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed polyamide . It
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#1732772498265492-450: Is from Old English ac (seen in placenames such as Acton , from ac + tun , "oak village"), which in turn is from Proto-Germanic *aiks , "oak". Oaks are hardwood ( dicotyledonous ) trees, deciduous or evergreen, with spirally arranged leaves , often with lobate margins ; some have serrated leaves or entire leaves with smooth margins. Many deciduous species are marcescent , not dropping dead leaves until spring. In spring,
533-519: Is the use of straw mixed with clay described in the Bible, Exodus 1:11 and that the Egyptians must have been aware of his (re-)discovery. He stated "This explains why the straw was used and why the children of Israel were successful in substituting stubble for straw, a course that would hardly be possible, were the fibre of the straw depended upon as a bond feasible for the clay, but quite reasonable where
574-643: The Paleogene , and possibly from before the Eocene are mostly poorly preserved without critical features for certain identification. Amongst the oldest unequivocal records of Quercus are pollen from Austria, dating to the Paleocene -Eocene boundary, around 55 million years ago. The oldest records of Quercus in North America are from Oregon , dating to the Middle Eocene, around 44 million years ago, with
615-852: The Royal Oak in Britain, the Charter Oak in the United States, and the Guernica Oak in the Basque Country . The generic name Quercus is Latin for "oak", derived from Proto-Indo-European *kwerkwu- , "oak", which is also the origin of the name " fir ", another important or sacred tree in Indo-European culture. The word "cork", for the bark of the cork oak , similarly derives from Quercus . The common name "oak"
656-436: The oak apple , and a large number of pests and diseases. Oak leaves and acorns contain enough tannin to be toxic to cattle, but pigs are able to digest them safely. Oak timber is strong and hard, and has found many uses in construction and furniture-making. The bark was traditionally used for tanning leather . Wine barrels are made of oak; these are used for aging alcoholic beverages such as sherry and whisky , giving them
697-706: The Old World, oaks of section Quercus extend across the whole of Europe including European Russia apart from the far north, and north Africa (north of the Sahara) from Morocco to Libya. In Mediterranean Europe, they are joined by oaks of the sections Cerris and Ilex , which extend across Turkey, the Middle East, Iran, Afghanistan and Pakistan , while section Ponticae is endemic to the western Caucasus in Turkey and Georgia . Oaks of section Cyclobalanopsis extend in
738-519: The West Indies (Cuba), and Central America. A 2017 classification included seven species: Species are native to Europe, north Africa and Asia. Styles long; acorns mature in 18 months, very bitter, inside of acorn shell hairless or slightly hairy. Species in section Ilex are native to Eurasia and northern Africa . Styles medium-long; acorns mature in 12–24 months, appearing hairy on the inside. Evergreen leaves, with bristle-like extensions on
779-462: The above-mentioned plants can be considered as tannic acid. Sometimes extracts from chestnut or oak wood are also described as tannic acid but this is an incorrect use of the term. It is a yellow to light brown amorphous powder. While tannic acid is a specific type of tannin (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably. The long-standing misuse of the terms, and its inclusion in scholarly articles has compounded
820-495: The acorns mature annually. The intermediate oaks . Southwest USA and northwest Mexico. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly. The red oaks (synonym sect. Erythrobalanus ), native to North, Central and South America. Styles long, acorns mature in 18 months (in most species), very bitter, inside of acorn shell woolly. Section Virentes has also been treated at lower ranks. Species are native south-eastern Northern America, Mexico,
861-429: The activation of upholstery flock; this serves as an anti- static treatment. Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches
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#1732772498265902-405: The confusion. This is particularly widespread in relation to green tea and black tea, both of which contain many different types of tannins not just exclusively tannic acid. Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition. Quercitannic acid is one of the two forms of tannic acid found in oak bark and leaves. The other form
943-468: The extract of the plant was used." Tannins are a basic ingredient in the chemical staining of wood , and are already present in woods like oak , walnut , and mahogany . Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react. The presence of tannins in the bark of redwood ( Sequoia) is a strong natural defense against wildfire , decomposition and infestation by certain insects such as termites . It
984-421: The fifth volume of "A dictionary of chemistry", Henry Watts wrote : It exhibits with ferric salts the same reactions as gallotannic acid. It differs however from the latter in not being convertible into gallic acid , and not yielding pyrogallic acid by dry distillation. It is precipitated by sulfuric acid in red flocks. ( Stenhouse , Ann. Ch. Pharm. xlv. 16.) According to Rochleder (ibid lxiii. 202),
1025-443: The formula given was C 19 H 16 O 10 . Other authors gave other molecular formulas like C 28 H 26 O 15 , while another formula found is C 28 H 24 O 11 . According to Lowe, two forms of the principle exist – "one soluble in water, of the formula C 28 H 28 O 14 , and the other scarcely soluble, C 28 H 24 O 12 . Both are changed by the loss of water into oak red, C 28 H 22 O 11 ." Quercitannic acid
1066-399: The genus Quercus consisted of Old World and New World clades. The entire genome of Quercus robur (the pedunculate oak) has been sequenced , revealing an array of mutations that may underlie the evolution of longevity and disease resistance in oaks. In addition, hundreds of oak species have been compared (at RAD-seq loci), allowing a detailed phylogeny to be constructed. However,
1107-639: The genus are often large and slow-growing; Q. alba can reach an age of 600 years, a diameter of 13 feet (4.0 m) and a height of 145 feet (44 m). The Granit oak in Bulgaria, a Q. robur specimen, has an estimated age of 1637 years, making it the oldest oak in Europe. The Wi'aaSal tree, a live oak in the reservation of the Pechanga Band of Indians , California, is at least 1000 years old, and might be as much as 2000 years old, which would make it
1148-481: The genus is divided into Old World and New World clades , but many oak species hybridise freely, making the genus's history difficult to resolve. Ecologically, oaks are keystone species in habitats from Mediterranean semi-desert to subtropical rainforest . They live in association with many kinds of fungi including truffles . Oaks support more than 950 species of caterpillar , many kinds of gall wasp which form distinctive galls , roundish woody lumps such as
1189-1140: The high signal of introgressive hybridization (the transfer of genetic material by repeated backcrossing with hybrid offspring) in the genus has made it difficult to resolve an unambiguous, unitary history of oaks. The phylogeny from Hipp et al. 2019 is: CTB lineage [REDACTED] Cyclobalanoides Glauca [REDACTED] Acuta [REDACTED] Semiserrata East Asian Cerris [REDACTED] West Eurasian Cerris [REDACTED] Early-diverging Ilex [REDACTED] East Asian Ilex [REDACTED] Himalaya-Mediterranean [REDACTED] Himalayan subalpine [REDACTED] Agrifoliae [REDACTED] Palustres [REDACTED] Coccineae (Rubrae) [REDACTED] Phellos (Laurifoliae) [REDACTED] Texas red oaks [REDACTED] Erythromexicana [REDACTED] [REDACTED] [REDACTED] [REDACTED] Dumosae [REDACTED] Prinoids [REDACTED] Albae [REDACTED] Roburoids [REDACTED] Stellatae [REDACTED] Texas white oaks [REDACTED] Leucomexicana [REDACTED] List of Quercus species Unless otherwise indicated,
1230-518: The largest number of oak species, with approximately 160 species in Mexico, of which 109 are endemic, and about 90 in the United States. The second greatest area of oak diversity is China, with approximately 100 species. In the Americas, Quercus is widespread from Vancouver and Nova Scotia in the south of Canada, south to Mexico and across the whole of the eastern United States. It is present in
1271-561: The lists which follow contain all the species accepted by Plants of the World Online as of February 2023 , plus selected hybrids that are also accepted, with placement into sections based on a list produced by Denk et al. for their 2017 classification of the genus. Species with evergreen foliage (" live oaks ") are tagged '#'. Species in the genus have been recategorized between deciduous and evergreen on numerous occasions, although this does not necessarily mean that species in
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1312-558: The oldest oak in the US. Among the smallest oaks is Q. acuta , the Japanese evergreen oak. It forms a bush or small tree to a height of some 30 feet (9.1 m). The genus Quercus is native to the Northern Hemisphere and includes deciduous and evergreen species extending from cool temperate to tropical latitudes in the Americas , Asia, Europe, and North Africa. North America has
1353-874: The oldest records in Asia from the Middle Eocene of Japan; both forms have affinities to the Cyclobalanopsis group. Quercus forms part, or rather two parts, of the Quercoideae subfamily of the Fagaceae , the beech family. Modern molecular phylogenetics suggests the following relationships: Fagus (beeches) Trigonobalanus (3 evergreen species) Lithocarpus (stone oaks) Chrysolepis (chinquapins) Quercus pro parte Notholithocarpus (tan oak) Quercus pro parte Castanopsis (also called chinquapins) Castanea (chestnuts) Molecular techniques for phylogenetic analysis show that
1394-458: The plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods ( Caesalpinia spinosa ), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves ( Rhus coriaria ). According to the definitions provided in external references such as international pharmacopoeia, Food Chemicals Codex and FAO-WHO tannic acid monograph only tannins obtained from
1435-442: The surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue. It should also be used with care on objects with copper alloy components as the tannic acid can have a slight etching effect on these metals. Tannic acid
1476-413: The tannic acid of black tea is the same as that of oak-bark. In 1880, Etti gave for it the molecular formula C 17 H 16 O 9 . He described it as an unstable substance, having a tendency to give off water to form anhydrides (called phlobaphenes ), one of which is called oak-red (C 34 H 30 O 17 ). For him, it was not a glycoside. In Allen's "Commercial Organic Analysis", published in 1912,
1517-418: The teeth. ( Sister group to sect. Cerris and sometimes included in it.) The ring-cupped oaks (synonym genus Cyclobalanopsis ), native to eastern and southeastern tropical Asia. They have corns with distinctive cups bearing concrescent rings of scales. They commonly also have densely clustered acorns, though this does not apply to all of the species. About 90 species. Tannic acid Tannic acid
1558-503: The two groups are closely related. Section Mesobalanus was included in section Quercus in the 2017 classification used here. Other synonyms include Q. sect. Albae and Q. sect. Macrocarpae . The section comprises the white oaks from Europe, Asia, north Africa, Central and North America. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless. Species are native to Western Asia and Western North America. They produce catkins up to 10cm long;
1599-711: The war this use was abandoned due to the development of more modern treatment regimens. Tannic acid could cause potential health hazards such as damage to the eye, skin, respiratory tract, and gastrointestinal tract. It may cause irritation, redness, pain, blurred vision, and possible eye damage. When tannic acid is absorbed through the skin in harmful amounts, it may cause irritation, redness, and pain. Nausea, vomiting and diarrhoea are symptoms of tannic acid ingestion and prolonged exposure may cause liver damage. Upon inhalation, tannic acid may cause respiratory tract irritation. Skin color in Crocodilia (crocodiles and alligators)
1640-414: Was for a time a standard used to assess the phenolic content in spices , given as quercitannic acid equivalent . In an interesting historical note, the inventor of carborundum , Edward G. Acheson , discovered that gallotannic acid greatly improved the plasticity of clay. In his report of this discovery in 1904 he noted that the only known historical reference to the use of organic material added to clay
1681-427: Was once used as a treatment for many toxic substances, such as strychnine , mushroom, and ptomaine poisonings in the late 19th and early 20th centuries. The introduction of tannic acid treatment of severe burn injuries in the 1920s significantly reduced mortality rates. During World War I , tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, mustard gas , or lewisite ". After