Tilia

Tilia
Tilia tomentosa, cultivated at the Morton Arboretum near Chicago
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Malvales
Family:	Malvaceae
Subfamily:	Tilioideae
Genus:	Tilia L.
Species
About 30

Tilia is a genus of about 30 species of trees native throughout most of the temperate Northern Hemisphere. Commonly called lime trees in the British Isles, they are not related to the lime fruit. Other names include linden, and basswood for the North American species.^[1] 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 20 to 40 metres (65 to 130 ft) tall, with oblique-cordate leaves 6 to 20 centimetres (2 ¹⁄₄ to 7 ³⁄₄ in) across. As with elms, the exact number of species is uncertain, as many if not most of the species will hybridise readily, both in the wild and in cultivation. Limes are hermaphroditic, having perfect flowers with both male and female parts, pollinated by insects.

Name

The genus is generally called lime or linden in Britain^[2] and linden, lime, or basswood in North America.^[3]

"Lime" is an altered form of Middle English lind, in the 16th century also line, from Old English feminine lind or linde, Proto-Germanic *lendā, 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"); 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.^[4] 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.^[5]

Description

Lime nail galls, caused by the mite Eriophyes tiliae

Leaves and trunk

The Tilia's 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.^[6]

The leaves of all the Tilia species are heart-shaped and most are asymmetrical, and the tiny fruit, looking like peas, always hang attached to a ribbon-like, greenish-yellow bract, whose use seems to be 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 bears a petal-like scale among its 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 the fall. If allowed to dry, the seeds will go into a deep dormancy and take 18 months to germinate.^[6]

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.

• 
  Leaf of common lime (Tilia × europaea) showing venation
• 
  Tilia flowers
• 
  Tilia fruit
• 
  The venation within a Tilia bract

History

T. johnsoni leaf fossil, 49 Ma, Washington, USA

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.^[7] 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.^[6] 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 (Slovene: Najevska lipa), a 700-year-old T. cordata, is the thickest tree in Slovenia.^[8]

• The excellence of the honey of far-famed Hyblaean Mountains^[9] 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.^[6]

Uses

Bombus terrestris on Tilia cordata

The linden is recommended as an ornamental tree when a mass of foliage or a deep shade is desired.^[6] The tree produces fragrant and nectar-producing flowers, the medicinal herb lime blossom. They are very important honey plants for beekeepers, producing a very pale but richly flavoured monofloral honey. The flowers are also used for herbal teas and tinctures; this kind of use is particularly popular in Europe and also used in North American herbal medicine practices.

Wood

Limewood Saint George by Tilman Riemenschneider, circa 1490

Linden trees produce soft and easily worked timber, which has very little grain and a density of 560 kg per cubic metre.^[10] 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^[11] (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 as of 2015.

Ease of working and good acoustic properties also make limewood popular for electric guitar and bass 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.

The aquarium industry uses lime wood as an air diffuser inside protein skimmers. Air pumped through the grain of the wood turns into consistently very fine bubbles (0.5–1.0 mm), difficult to achieve with any other natural or man-made medium. However, the wood decomposes underwater much faster than ceramic air stones and must be replaced more frequently for maximum efficiency.

Limewood 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^[12] 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 tree has been used by the Ainu people of Japan to weave their traditional clothing, the attus. Recent excavations in Britain have shown that "lime tree fiber" was preferred for clothing there during the Bronze Age. Similar fibres obtained from other plants are also called bast: see Bast fibre.

Herbalism

The dried flowers are mildly sweet and sticky, and the fruit is somewhat sweet and mucilaginous. Limeflower tea has a pleasing taste, due to the aromatic volatile oil found in the flowers. The flowers, leaves, wood, and charcoal (obtained from the wood) are used for medicinal purposes. Active ingredients in the Tilia flowers include flavonoids (which act as antioxidants) and volatile oils. The plant also contains tannins that can act as an astringent.^[13]

Linden flowers are used in herbalism for colds, cough, fever, infections, inflammation, high blood pressure, headache (particularly migraine), and as a diuretic (increases urine production), antispasmodic (reduces smooth muscle spasm along the digestive tract), and sedative.^[14] In the traditional Austrian medicine Tilia sp. flowers have been used internally as tea for treatment of disorders of the respiratory tract, fever and flu.^[15] New evidence shows that the flowers may be hepatoprotective.^[16] The wood is used for liver and gallbladder disorders and cellulitis (inflammation of the skin and surrounding soft tissue). That wood burned to charcoal is ingested to treat intestinal disorders and used topically to treat edema or infection such as cellulitis or ulcers of the lower leg.^[13]

Usually, the double-flowered species are used to make perfumes. The leaf buds and young leaves are also edible raw.^[17][18] Tilia species are used as food plants by the larvae of some Lepidoptera; see List of Lepidoptera that feed on Tilia.

Classification

The following list comprises those most widely accepted as species, hybrids, and cultivars.

Bole of an ancient Tilia at Frankenbrunn, Bavaria

Ancient lime tree at Chilston Park, England

Avenue of lime trees at Turville Heath

15-year-old lime-tree, Haute-Savoie, France

Species

• Tilia americana L. – Basswood, American Linden
• Tilia amurensis – Amur Lime, Amur Linden
• Tilia caroliniana – Carolina Basswood
• Tilia chinensis
• 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 heterophylla Vent. – White Basswood
• 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 mexicana (T. americana var. mexicana)
• Tilia miqueliana
• Tilia mongolica Maxim. –Mongolian Lime, Mongolian Linden
• Tilia nasczokinii – Nasczokin's Lime, Nasczokin's Linden
• Tilia nobilis
• Tilia occidentalis – West lime
• 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

• 
  Tilia americana
• 
  Tilia cordata
• 
  Tilia henryana
• 
  Tilia heterophylla (syn. T. monticola)
• 
  Tilia insularis
• 
  Tilia japonica
• 
  Tilia maximowicziana
• 
  Tilia miqueliana
• 
  Tilia mongolica
• 
  Tilia oliveri
• 
  Tilia platyphyllos
• 
  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
• St Lawrence Lime, a former lime tree in Canterbury, England
• Lime tree in culture

References

Bibliography

External links

Wikisource has the text of the 1920 Encyclopedia Americana article Linden.

• Eichhorn, Markus (January 2012). "Lime Trees and Bees". Test Tube. Brady Haran for the University of Nottingham.