Tilia americana

From Wikipedia, the free encyclopedia

Tilia americana

Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malvales
Family: Malvaceae
Genus: Tilia
Species: T. americana
Binomial name
Tilia americana
L.

Tilia americana is a species of Tilia, native to eastern North America, from southeast Manitoba east to New Brunswick, southwest to northeast Texas, and southeast to South Carolina, and west along the Niobrara River to Cherry County, Nebraska.[1][2] Common names include Basswood (also applied to other species of Tilia in the timber trade) and American Linden or the Lime-Tree.

Contents

[edit] Description

It is a medium-sized to large deciduous tree reaching a height of 20-40 m (exceptionally 43 m) with a trunk diameter of 1-1.3 m at maturity. The crown is domed, the branches spreading, often pendulous. The bark is gray to light brown, with narrow, well defined fissures. The roots are large, deep, and spreading. The twigs are smooth, reddish-green, becoming light gray in their second year, finally dark brown or brownish gray, marked with dark wart-like excrescences. The winter buds are stout, ovate-acute, smooth, deep red, with two bud scales visible. The leaves are simple, alternately arranged, ovate to cordate, inequalateral at the base (the side nearest the branch the largest), 10-15 cm (exceptionally 25 cm) long and broad, with a long, slender petiole, a coarsely serrated margin and an acuminate apex. They open from the bud conduplicate, pale green, downy; when full grown are dark green, smooth, shining above, paler beneath, with tufts of rusty brown hairs in the axils of the primary veins; the small stipules fall soon after leaf opening. The fall color is yellow-green to yellow. Both the twigs and leaves contain mucilaginous sap. The flowers are small, fragrant, yellowish-white, 10–14 mm diameter, arranged in drooping, cymose clusters of 6–20 with a whitish-green leaf-like bract attached for half its length at the base of the cyme; they are perfect, regular, with five sepals and petals, numerous stamens, and a five-celled superior ovary. Flowering is in early to mid summer; pollination is by bees. The fruit is a small, globose, downy, hard and dry cream-colored nutlet with a diameter of 8-10 mm.[1][3][4]

[edit] Taxonomy

The circumscription of the species is disputed; some authors[1][5] treat it in a narrow sense, with Tilia caroliniana, Tilia heterophylla, and Tilia mexicana regarded as separate species, while others[2][6][7] treat these as varieties or synonyms of T. americana. The distribution and description above treat the species in its narrow sense; in the broad sense, the distribution extends southwards to Florida, and in Mexico west to Sinaloa and south to Oaxaca, and includes plants with the leaves white below with dense tomentum (velvety hairs).

[edit] Ecology

This species is dominant in the Acer saccharum - Tilia americana association, most common in western Wisconsin and central Minnesota, but occurs as far east as New England and southern Quebec where the soils are mesic with relatively high pH. It also has minor occurrence in many other forest cover types.

Its flowers provide abundant nectar for insects. The seeds are eaten by chipmunks, mice and squirrels. Rabbits and voles eat the bark, sometimes girdling young trees. This species is particularly susceptible to adult Japanese beetles (an invasive species in the species' range) feeding on its leaves.[8] In addition, the leaves serve as food for caterpillars of various Lepidoptera (see Lepidoptera which feed on Tilia). The ribbed cocoon maker species Bucculatrix improvisa has not been found on other plants.

[edit] Cultivation and uses

It may be propagated by cuttings and grafting as well as by seed. They grow rapidly in a rich soil, but are subject to the attacks of many insect enemies.

It is recommended as an ornamental tree when the mass of foliage or a deep shade is desired; no native tree surpasses it in this respect. It is often planted on the windward side of an orchard as a protection to young and delicate trees.[4] It is cultivated at least as far north as Juneau, Alaska.[9]

Cultivars include 'Nova', 'Duros' (with an upright crown), and the conic-crowned 'Redmond'.

[edit] Wood and bark

The wood is pale brown, sometimes nearly white or faintly tinged with red; light, soft with fine close grain; clear of knots but does not split easily. It is sold generally under the name basswood, but is sometimes confounded with tulip-wood and then called white-wood, and is largely used in the manufacture of wooden-ware, wagon boxes and furniture. It has a density of 0.4525. This makes it valuable in the manufacture of wooden-ware, cheap furniture, bodies of carriages; it is also especially adapted for wood-carving. Bees produce excellent honey from its blossoms. The inner bark is very tough and fibrous, used in the past for making ropes.[4]

[edit] Medicinal Uses

Although Tilia cordata is believed to be stronger, T. americana is also used medicinally. The dried flowers are mildly sweet and sticky, and the fruit is somewhat sweet and mucilaginous. Linden 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 linden flowers include flavanoids (which act as antioxidants), volatile oils, and mucilaginous constituents (which soothe and reduce inflammation). The plant also contains tannins that can act as an astringent.[10]

Linden flowers are used in colds, cough, fever, infections, inflammation, high blood pressure, headache (particularly migraine), as a diuretic (increases urine production), antispasmodic (reduces smooth muscle spasm along the digestive tract), and sedative. The flowers were added to baths to quell hysteria, and steeped as a tea to relieve anxiety-related indigestion, irregular heartbeat, and vomiting. The leaves are used to promote sweating to reduce fevers. 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.[10][11]

[edit] See also

Bois Blanc Island (Michigan)

[edit] References

  1. ^ a b c U.S. Forest Service Silvis Manual: Tilia americana
  2. ^ a b Germplasm Resources Information Network: Tilia americana
  3. ^ USDA NRCS Tree Guide: Tilia americana (pdf file)
  4. ^ a b c Keeler, H. L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons, 24-31. 
  5. ^ Jones, G. N. (1968). Taxonomy of the American species of linden (Tilia). Illinois Biological Monographs 39. University of Illinois Press, Urbana.
  6. ^ Hardin, J. W. (1990). Variation patterns and recognition of varieties of Tilia americana s.l. Syst. Bot. 15: 33-48. Abstract.
  7. ^ Bioimages: Tillia americana ssp. heterophylla
  8. ^ USDA: Managing Japanese beetles
  9. ^ Juneau: Downtown Juneau Tree Guide
  10. ^ a b Bradley P, ed. British Herbal Compendium. Vol. I. Dorset (Great Britain): British Herbal Medicine Association; 1992: 142-144
  11. ^ Aguirre-Hernandez, E., Martinez, A. L., Gonzalez-Trujano, M. E., Moreno, J., Vibrans, H., & Soto-Hernandez, M. (2007). Pharmacological evaluation of the anxiolytic and sedative effects of Tilia americana L. var. mexicana in mice. J. Ethnopharmacol. 109 (1): 140-145.