Various species of Tilia, or lime trees, have been used in European folk medicine for centuries to treat a wide range of health conditions. Also known as basswood, Tilia species are native to the northern temperate regions. Lime trees are valued not only as raw material for botanical therapies, but also as a commercial source of wood and charcoal.

Most linden herbal remedies consist of the flowers, but the leaves, wood, and charcoal are also used medicinally. The light charcoal is administered for gastric and dyspeptic complaints while powdered charcoal is applied topically to burns. A honey made from linden flowers is highly touted for its flavor and quality.

Linden flower tea is traditionally used as a diaphoretic (promotes perspiration). Precise structure-activity relations for the diaphoretic properties of Tilia species have not yet been elucidated. However, the diaphoretic activity has been attributed to p-coumaric acid and several flavonoid constituents, including quercetin- and kaempferol-derivatives.

Linden flower formulas typically call for either Tilia cordata, the small-leafed European linden, or Tilia platyphyllos, the large-leafed linden. These two species furnish the bulk of commercial linden flowers. A related species, Tilia tomentosa, the silver linden, is sometimes employed in linden leaf preparations, but not in linden flower remedies. Tilia cordata, also called the winter linden, flowers about two weeks earlier than Tilia platyphyllos, the early-blooming summer linden. Both species are frequently planted as ornamental trees along city streets.

Linden flower tea is a popular remedy for treating headaches, indigestion, hysteria, and diarrhea. It reportedly has antispasmodic, hypotensive, emollient, and mildly astringent properties. In addition, linden flower possesses opposing pharmacological activities, acting as both a sedative and stimulant.

Linden tea has a pleasing taste, presumably because of the interaction of astringent tannins with mucilage and an aromatic volatile oil in the flowers. Since the slightest amount of moisture decreases their aromatic effects, the fragrant flowers must be quickly dried in the shade after they are collected during late spring.

The taste of linden tea can also influence its therapeutic effects. Taste is crucial because large quantities of the tea must be consumed to promote perspiration, for example, during feverish colds. Patients are more likely to drink linden teas that are more palatable, and the better-tasting teas are those with a relatively higher tannin (minimum 2.0%) and a lower mucilage content. Tilia cordata and Tilia platyphyllos are preferable sources of linden flower because they contain larger quantities of tannin and lower amounts of mucilage than other Tilia species such as the silver linden.

Linden species are large deciduous trees that can grow to a height of 25 to 33 meters. The yellowish-white flowers of Tilia cordata are arranged in clusters of 5 to 11 in cymes that hang from slender stalks. Their potent and sweet fragrance contrasts with the profusely rich scent of Tilia tomentosa. The dried inflorescences are mildly sweet and mucilaginous to the palate, while the fruit has a somewhat sweet, slimy, and dry taste.

The long-petioled leaves of linden are broadly cordate with an uneven base. Tilia platyphyllos is characterized by obliquely heart-shaped, broad leaves that are paler on the underside and dark green on the upperside. The bark of linden trees is fissured and either gray-brown or black-gray. Tilia cordata has a relatively shorter trunk and tougher leaves than does Tilia platyphyllos. Tilia cordata can live to 1,000 years, and its smooth brown bark roughens with age.

• Fresh and dried flowers
• Dried leaves
• Wood

• Leaves (Tilia spp.): flavonoids, including linarin (acacetin-7-rutinosides); tannins, mucilage
• Flowers (Tilia spp.): flavonoids, including rutin, hyperoside, quercitrin, isoquercitrin, astragalin, tiliroside; mucilage, volatile oil containing linalool, geraniol, 1,8-cineole, 2-phenyl ethanol; caffeic acid derivatives, tannins
• Flowers (Tilia tomentosa): flavonoids, including hyperoside; hydroxycoumarins, including calycanthoside, aesculin; caffeic acid derivatives (chlorogenic acid); mucilage
• Charcoal (Tilia spp.): source of exceedingly absorbent charcoals
• Wood (Tilia spp.): mucilage, sterols, triterpenes

Linden preparations are made primarily from the dried flower, particularly of Tilia cordata and Tilia platyphyllos. Flowers should always be stored in airtight, light-resistant containers in order to preserve their maximum fragrance. Commercial preparations manufactured from authenticated Tilia cordata and Tilia platyphyllos are considered superior.

• Flowers: colds, cough, bronchitis, diaphoretic to promote sweating during feverish common colds and infectious diseases; also used as diuretic, stomachic, antispasmodic, sedative
• Tilia tomentosa flowers: respiratory tract catarrhs, antispasmodic, expectorant, diaphoretic, diuretic
• Leaf: diaphoretic
• Charcoal: (internal) intestinal complaints; (external) crural (leg-related) ulcers
• Wood: liver and gallbladder disorders, cellulitis
• Mild hypertension
• Tension headaches

Conditions: upper respiratory catarrh, common cold, irritable cough, hypertension, restlessness, headache, migraine; topically for skin ailments.

Clinical applications: diaphoretic; flowers incorporated into some standardized urological, antitussive, and sedative preparations.

Pharmacological investigations on Tilia species are limited. In earlier in vivo research, flower extracts administered i.v. to test animals produced hypotensive and vasodilative effects, increased pulse rate, and decreased cardiac tone. While specific mechanisms of action have not been determined for pharmacological activity, some general structure-activity relationships have been described. Flavonoids, glycosides, and phenolic acids are reportedly responsible for the diaphoretic action of linden flower.

Since mucilages are known to elicit emollient effects, these compounds may account for the antitussive activity of linden flower tea. The wound-healing effects are probably due to the astringent properties of the tannins in linden. Although the volatile oil contains only a small quantity of farnesol, this active principle may stimulate the sedative and antispasmodic effects of linden.

Other research suggests that the diaphoretic activity of linden flower tea derives in part from thermal influences, especially the heated beverage itself and the bodily warmth that comes from bed rest. In one study, diaphoresis seemed to have a diurnal pattern. Profuse perspiration was associated with heat applied in the afternoon and evening, but not in the morning.

Tea (infusion): 1 to 2 tsp. flowers in 8 oz. water; steep covered 20 minutes; drink three cups/day hot

Fluid extract (1:1, 25% ethanol): 2 to 4 ml tid

Tincture (1:5, 30% ethanol): 4 to 10 ml tid

None reported for either flower or leaf.

The flower and leaf are considered safe when used as directed. However, since excessive use of linden flower tea may cause cardiac complications, this plant should be avoided by persons with heart problems. An account stating that tea from very old linden flowers may induce narcotic intoxication has not been substantiated and should be considered invalid.

No clinically significant interactions between linden and conventional medications are known to have been reported in the literature to date, including the German Commission E monograph (Blumenthal 1998).

German Commission E lists linden flower as an approved herb, and linden leaf as an unapproved herb. Although the clinical effectiveness of leaf preparations has not been documented, German Commission E permits the use of the leaves as a filler in tea mixtures.

In the United Kingdom, linden flower appears on the General Sale List, Schedule 2, Table A [R1a]. Linden is recognized as safe in the United States, and the Council of Europe has approved its use as a flavoring.

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