Linden trees

''Tilia'' is a genus of about 30 species of trees or bushes, native throughout most of the temperate Northern Hemisphere. The tree is known as linden for the European species, and basswood for North American species. In Britain and Ireland they are commonly called lime trees, although they are not related to the citrus lime. The genus occurs in Europe and eastern North America, but the greatest species diversity is found in Asia. Under the Cronquist classification system, this genus was placed in the family Tiliaceae, but genetic research summarised by the Angiosperm Phylogeny Group has resulted in the incorporation of this genus, and of most of the previous family, into the Malvaceae.

''Tilia'' species are mostly large, deciduous trees, reaching typically tall, with oblique-cordate (heart-shaped) leaves across. As with elms, the exact number of species is uncertain, as many of the species can hybridise readily, both in the wild and in cultivation. They are hermaphroditic, having perfect flowers with both male and female parts, pollinated by insects.

''Tilia'' is the only known ectomycorrhizal genus in the family Malvaceae. Studies of ectomycorrhizal relations of ''Tilia'' species indicate a wide range of fungal symbionts and a preference toward Ascomycota fungal partners.

Name

The genus is generally called "lime" or "linden" in Britain and "linden", "lime", or "basswood" in North America.

"Lime" is an altered form of Middle English ''lind'', in the 16th century also ''line'', from Old English feminine ''lind'' or ''linde'', Proto-Germanic ''*lindō'', cognate to Latin ''lentus'' "flexible" and Sanskrit ''latā'' "liana". Within Germanic languages, English "lithe", German ''lind'' "lenient, yielding" are from the same root.

"Linden" was originally the adjective, "made from linwood or lime-wood" (equivalent to "wooden" or "oaken"); from the late 16th century, "linden" was also used as a noun, probably influenced by translations of German romance, as an adoption of ''Linden'', the plural of German ''Linde''.
Neither the name nor the tree is related to the citrus fruit called "lime" (''Citrus aurantifolia'', family Rutaceae). Another common name used in North America is basswood, derived from ''bast'', the name for the inner bark (see Uses, below). Teil is an old name for the lime tree.

Latin ''tilia'' is cognate to Greek πτελέᾱ, ''ptelea'', "elm tree", τιλίαι, ''tiliai'', "black poplar" ( Hes.), ultimately from a Proto-Indo-European word ''*ptel-ei̯ā'' with a meaning of "broad" (feminine); perhaps "broad-leaved" or similar.

Description

The ''Tilia'' sturdy trunk stands like a pillar and the branches divide and subdivide into numerous ramifications on which the twigs are fine and thick. In summer, these are profusely clothed with large leaves and the result is a dense head of abundant foliage.

The leaves of all the ''Tilia'' species are heart-shaped, and most are asymmetrical. The tiny, pea-like fruit hangs attached to a ribbon-like, greenish-yellow bract whose apparent purpose is to launch the ripened seed clusters just a little beyond the parent tree. The flowers of the European and American ''Tilia'' species are similar, except the American ones bear a petal-like scale among their stamens and the European varieties are devoid of these appendages. All of the ''Tilia'' species may be propagated by cuttings and grafting, as well as by seed. They grow rapidly in rich soil, but are subject to the attack of many insects. ''Tilia'' is notoriously difficult to propagate from seed unless collected fresh in fall. If allowed to dry, the seeds go into a deep dormancy and take 18 months to germinate.

In particular, aphids are attracted by the rich supply of sap, and are in turn often "farmed" by ants for the production of the sap, which the ants collect for their own use, and the result can often be a dripping of excess sap onto the lower branches and leaves, and anything else below. Cars left under the trees can quickly become coated with a film of the syrup ("honeydew") thus dropped from higher up. The ant/aphid "farming" process does not appear to cause any serious damage to the trees.

File:Tilia x cordata leaf underside.JPG, Leaf of common lime (''Tilia × europaea'') showing venation
File:Lime tree.jpg, ''Tilia'' flowers
File:Tilia cordata Owoce lipy 656.jpg, ''Tilia'' fruit
File:Tilia x cordata flower veination.JPG, The venation within a ''Tilia'' bract

History

In Europe, some linden trees reached considerable ages. A coppice of ''T. cordata'' in Westonbirt Arboretum in Gloucestershire is estimated to be 2,000 years old. In the courtyard of the Imperial Castle at Nuremberg is a ''Tilia'', which by tradition recounted in 1900, was planted by the Empress Cunigunde, the wife of Henry II of Germany ''circa'' 1000. The ''Tilia'' of Neuenstadt am Kocher in Baden-Württemberg, Germany, was estimated at 1000 years old when it fell. The Alte Linde tree of Naters, Switzerland, is mentioned in a document in 1357 and described by the writer at that time as already ''magnam'' (large). A plaque at its foot mentions that in 1155, a linden tree was already on this spot. The Najevnik linden tree ( sl, Najevska lipa), a 700-year-old ''T. cordata'', is the thickest tree in Slovenia.

* The excellence of the honey of the far-famed Hyblaean Mountains was due to the linden trees that covered its sides and crowned its summit.
* Lime fossils have been found in the Tertiary formations of Grinnell Land, Canada, at 82°N latitude, and in Svalbard, Norway. Sapporta believed he had found there the common ancestor of the ''Tilia'' species of Europe and America.

Uses

The linden is recommended as an ornamental tree when a mass of foliage or a deep shade is desired. It produces fragrant and nectar-producing flowers and is an important honey plant for beekeepers, giving rise to a pale but richly flavoured monofloral honey. In European and North American herbal medicine, the flowers are also used for herbal teas and tinctures. The flowers are used for herbal tea in the winter in Greece and Turkey.

In English landscape gardens, avenues of linden trees were fashionable, especially during the late 17th and early 18th centuries. Many country houses have a surviving "lime avenue" or "lime walk", the example at Hatfield House was planted between 1700 and 1730. The fashion was derived from the earlier practice of planting lindens in lines as shade trees in Germany, the Netherlands, Belgium and northern France. Most of the trees used in British gardens were cultivars propagated by layering in the Netherlands.

Wood

Linden trees produce soft and easily worked timber, which has very little grain and a density of 560 kg/m³. It was often used by Germanic tribes for constructing shields. It is a popular wood for model building and for intricate carving. Especially in Germany, it was the classic wood for sculpture from the Middle Ages onwards and is the material for the elaborate altarpieces of Veit Stoss, Tilman Riemenschneider, and many others. In England, it was the favoured medium of the sculptor Grinling Gibbons (1648–1721). The wood is used in marionette- and puppet-making and -carving. Having a fine, light grain and being comparatively light in weight, it has been used for centuries for this purpose; despite the availability of modern alternatives, it remains one of the main materials used .

Ease of working and good acoustic properties also make limewood popular for electric and bass guitar bodies and for wind instruments such as recorders. Percussion manufacturers sometimes use ''Tilia'' as a material for drum shells, both to enhance their sound and for their aesthetics.

Linden wood is also the material of choice for window blinds and shutters. Real-wood blinds are often made from this lightweight but strong and stable wood, which is well suited to natural and stained finishes.

Bark

Known in the trade as basswood, particularly in North America, its name originates from the inner fibrous bark of the tree, known as bast. A strong fibre is obtained from the tree by peeling off the bark and soaking it in water for a month, after which the inner fibres can be easily separated. Bast obtained from the inside of the bark of the ''Tilia japonica'' tree has been used by the Ainu people of Japan to weave their traditional clothing, the ''attus''. Excavations in Britain have shown that lime tree fibre was preferred for clothing there during the Bronze Age. Similar fibres obtained from other plants are also called bast: see Bast fibre.

Phytochemicals and folk medicine

The dried flowers are mildly sweet and sticky, and the fruit is somewhat sweet and mucilaginous. Linden flower tea has a pleasing taste, due to the aromatic volatile oil found in the flowers. Phytochemicals in the ''Tilia'' flowers include flavonoids and tannins with astringent properties.Bradley P., ed. (1992). British Herbal Compendium. Vol. 1: 142–144. British Herbal Medicine Association, Dorset (Great Britain) In traditional medicine, ''Tilia'' flowers have been used as tea for treatment of respiratory diseases.

In his compendium ''Food for Free'', Richard Mabey includes a recipe for tilleul tea, popular in France, made with the flowers of the Lime tree, described as "one of the very best teas of all wild flowers" and notes that the tree's leaves can be eaten in salad or as a sandwich filling.

The nectar contains a major secondary metabolite with the trivial name tiliaside (1--(1-hydroxy-1-methylethyl)-1,3-cyclohexadiene-1-carboxylate6-O-β-D-glucopyranosyl-β-D-glucopyranose) which is transformed in the gut of bumble bees to the aglycone (i.e., the gentiobiose group is cleaved) which is bioactive against a common and debilitating gut parasite of bumble bees, ''Crithidia bombi''. This naturally occurring compound may support bees to manage the burden of disease - one of the major contributors to pollinator decline.

Other uses

Usually, the double-flowered species are used to make perfumes. The leaf buds and young leaves are also edible raw.

''Tilia'' species are used as food plants by the larvae of some Lepidoptera; see List of Lepidoptera that feed on ''Tilia''.

Classification

This list comprises the most widely accepted species, hybrids, and cultivars".

Species

* ''Tilia americana'' L. – American basswood, American linden
* ''Tilia amurensis'' – Amur lime, Amur linden
* ''Tilia caroliniana'' – Carolina basswood
* ''Tilia chinensis'' – Chinese linden
* '' Tilia chingiana'' Hu & W.C.Cheng
* ''Tilia cordata'' Mill. – Small-leaved lime, little-leaf linden or greenspire linden
* '' Tilia dasystyla'' Steven
* ''Tilia henryana'' Szyszyl. – Henry's lime, Henry's linden
* '' Tilia hupehensis'' – Hubei lime
* '' Tilia insularis''
* ''Tilia intonsa''
* ''Tilia japonica'' – Japanese lime, ''shina'' (when used as a laminate)
* †'' Tilia johnsoni'' Wolfe & Wehr Eocene; Washington and British Columbia
* '' Tilia kiusiana''
* '' Tilia mandshurica'' – Manchurian lime
* ''Tilia maximowicziana''
* '' Tilia miqueliana''
* ''Tilia mongolica'' Maxim. – Mongolian lime, Mongolian linden
* ''Tilia nasczokinii'' – Nasczokin's lime, Nasczokin's linden
* '' Tilia nobilis''
* '' Tilia officinarum''
* '' Tilia oliveri'' – Oliver's lime
* '' Tilia paucicostata''
* ''Tilia platyphyllos'' Scop. – large-leaved lime
* ''Tilia rubra'' – Red stem lime (syn. ''T. platyphyllos'' var. ''rubra'')
* ''Tilia tomentosa'' Moench – silver lime, silver linden
* ''Tilia tuan'' Szyszyl.

Hybrids and cultivars

* '' Tilia × euchlora'' (''T. dasystyla × T. cordata'')
* ''Tilia × europaea'' – Common lime (''T. cordata × T. platyphyllos''; syn. ''T. × vulgaris'')
* ''Tilia × petiolaris'' (''T. tomentosa × T. ?'')
* ''Tilia'' 'Flavescens' – Glenleven linden (''T. americana × T. cordata'')
* ''Tilia'' 'Moltkei' (''T. americana × T. petiolaris'')
* ''Tilia'' 'Orbicularis' (hybrid, unknown origin)
* ''Tilia'' 'Spectabilis' (hybrid, unknown origin)

Gallery

File:AmericanBasswood.JPG, ''Tilia americana''
File:Tilia-cordata2.JPG, ''Tilia cordata''
File:Tilia henryana.jpg, ''Tilia henryana''
File:Tilia monticola JPG1FeA.jpg, ''Tilia heterophylla'' (syn. ''T. monticola'')
File:Tilia insularis 3.jpg, '' Tilia insularis''
File:Tilia japonica.JPG, ''Tilia japonica''
File:Tilia maximowicziana 1.JPG, ''Tilia maximowicziana''
File:Tilia miqueliana3.jpg, '' Tilia miqueliana''
File:Tilia mongolica0.jpg, ''Tilia mongolica''
File:Tilia oliveri JPG1Fe.jpg, '' Tilia oliveri''
File:20140508Tilia platyphyllos3.jpg, ''Tilia platyphyllos''
File:Tilia-tomentosa.JPG, ''Tilia tomentosa''

See also

* International World War Peace Tree, a ''Tilia'' tree that stands as a sign of Germany's armistice with the United States
* Lime tree in culture
* Matryoshka doll, made from linden trees
* St Lawrence Lime, a former lime tree in Canterbury, England

References

Bibliography

*

External links

*
*

{{Authority control

Malvaceae genera
Medicinal plants
Taxa named by Carl Linnaeus