Tilia


Tilia is a genus of about 30 species of trees or bushes, native throughout most of the temperate Northern Hemisphere. The species are known as linden or lime for the European and Asian species, and linden or basswood for North American species and more generally in American literature. The greatest species diversity is found in Asia, but the genus also occurs widely in Europe and eastern North America. 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 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.

Description

Tilia species are mostly large, deciduous trees, reaching typically tall. 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.
The trunk is stout, with pale grey to brownish-grey bark, smooth at first, becoming coarsely fissured or scaly on older trees; the inner bark, called bast, is soft, but fibrous, with high tensile strength. The wood is white, fairly soft, with minimal wood grain, making it popular for wood carving.
The leaves of Tilia species are heart-shaped, and most are asymmetrical, with oblique-cordate leaves across, sometimes more, to 25 cm in the hybrid cultivar Tilia 'Moltkei'. In all species, the leaf margin is toothed, sometimes markedly so, with T. henryana having conspicuous long bristle-like teeth up to 4.4 mm long. In another species, T. mongolica, the leaves are also distinctly three- to five-lobed as one or two pairs of the marginal teeth are larger than the others; in this species, the leaf base is also usually symmetrical, not oblique as in other limes.
The flowers are small and symmetrical, with five sepals and five petals; the petals are yellow to greenish-yellow, about twice the length of the sepals when fully open; they are strongly scented, and very attractive to bees and other insects. The flowers of European and American Tilia species are similar, except the American ones bear a petal-like scale among their stamens and the European species are devoid of these appendages. The tiny, pea-sized fruit hangs attached to a ribbon-like, greenish-yellow bract whose apparent purpose is to aid the ripened seed clusters to blow in wind to a little beyond the parent tree. The fruit is mostly smooth and variably downy, but in T. chinensis and T. platyphyllos is prominently ribbed, with five ribs. 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 damage by several insects. Tilia is notoriously difficult to propagate from seed unless collected fresh in autumn; if allowed to dry, the seeds go into deep dormancy and take 18 months to germinate.

Taxonomy

Subdivision

Species

This list comprises the species accepted by the Plants of the World Online :
  • Tilia americana L. – American basswood, American linden
  • Tilia amurensis – Amur lime, Amur linden
  • Tilia callidonta
  • Tilia chinensis – Chinese lime or Chinese linden
  • Tilia chingiana Hu & W.C.Cheng
  • Tilia concinna
  • Tilia cordata Mill. – small-leaved lime
  • Tilia dasystyla Steven
  • Tilia endochrysea
  • Tilia henryana Szyszyl. – Henry's lime, Henry's linden
  • Tilia hyrcana – Hubei lime
  • Tilia japonica – Japanese lime, shina
  • Tilia jiaodongensis
  • Tilia kiusiana
  • Tilia kueichouensis
  • Tilia likiangensis
  • Tilia mandshurica – Manchurian lime
  • Tilia maximowicziana
  • Tilia membranacea
  • Tilia mexicana
  • Tilia miqueliana
  • Tilia mongolica Maxim. – Mongolian lime, Mongolian linden
  • Tilia nobilis – noble lime
  • Tilia occidentalisibirica
  • Tilia oliveri – Oliver's lime
  • Tilia paucicostata
  • Tilia platyphyllos Scop. – large-leaved lime
  • Tilia sabetii
  • Tilia stellatopilosa
  • Tilia toboliensis
  • Tilia tomentosa Moench – silver lime
  • Tilia tuan Szyszyl.
The following additional species have been accepted by some other sources:
  • Tilia caroliniana – Carolina basswood
  • Tilia hupehensis
  • ''Tilia nasczokinii''

    Hybrids

These natural hybrids are also accepted by POWO:
  • Tilia × cinerascens
  • Tilia × euchlora
  • Tilia × europaea – Common lime
  • Tilia × haynaldiana
  • Tilia × juranyiana
  • ''Tilia × noziricola''

    Extinct species

  • †Tilia johnsoni Wolfe & Wehr Eocene; Washington and British Columbia

    Selected cultivars

  • Tilia 'Flavescens' – Glenleven linden
  • Tilia 'Moltkei'
  • Tilia 'Orbicularis'
  • Tilia 'Petiolaris'
  • Tilia 'Spectabilis'

    Etymology

The Latin tilia is cognate to Greek πτελέᾱ, ptelea, "elm tree", τιλίαι, tiliai, "black poplar", ultimately from a Proto-Indo-European word *ptel-ei̯ā with a meaning of "broad" ; perhaps "broad-leaved" or similar.
The genus is generally called "lime" in Britain and "linden", 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" and Dutch/German lind for "lenient, yielding" are from the same root.
"Linden" was originally the adjective, "made from linwood or lime-wood" ; 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 Linde in Dutch and German.
Neither the name nor the tree is related to Citrus genus species and hybrids that go by the same name, such as Key limes. Another common name used in North America is basswood, derived from bast, the name for the inner bark. Teil is an old name for the lime tree.

Ecology

Aphids are attracted by the rich supply of sap, and are in turn often "farmed" by ants for the production of the honeydew, 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 thus dropped from higher up. The ant/aphid "farming" process does not appear to cause any serious damage to the trees.

Uses

Limes are widely used as ornamental trees 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 the Balkans. In China, dried Tilia flowers are also used to make tea.
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 sculptor Grinling Gibbons. 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. In China, it was also widely used in carving or furniture, interior decorating, handicrafts, etc.
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.
In China, 冻蘑/"dongmo" grows well on decomposing logs of Tilia trees in the old-growth forest; therefore, people use logs of Tilia trees to cultivate S. edulis and even black fungus or shiitake mushrooms with excellent results. Currently, "椴木黑木耳/Tilia-logs-black fungus" or "椴木香菇/Tilia-logs-shiitake mushrooms" has become a term for a method of cultivating black fungus and shiitake mushrooms and "椴木/Tilia-logs" no longer exclusively refers to Tilia tree wood but also to other woods suitable for black fungus or shiitake mushrooms cultivation.
In Russian, "linden-made" is a term for forgery, due to the popularity of the material for making forged seals in the past centuries.