Linden (genus Tilia, aka Basswood in the U.S. or Lime in the U.K.), is an attractive and useful tree with no major drawbacks. The name “Basswood” is probably derived from the word “bast”, the inner bark which was once a major source of fiber. Prized for carving and for landscaping, it has a subtle, but unmistakable appearance in summer, with its yellow-green bracts against dark green leaves.
Linden Leaves
Linden leaves are alternately attached and simple. Opposite leaves (and branches) are attached to the tree directly across from one another, while alternate leaves are not. The opposite trees in Ohio are the MADBucks – Maple, Ash, Dogwood, Buckeye. The rest, except for a few shrubby trees, are alternately arranged.
The leaves are mostly pinnately veined, but there are several palmate veins near the leaf base. Pinnately veined leaves (feather-like) have a single primary vein with secondary veins attached at different points along its length. Palmately-veined (hand-like) leaves have several primary veins attached at the base, like the attachment of the fingers on a person’s hand.
Linden leaves are nearly round or heart-shaped (chordate), and typically have lopsided (oblique) bases. The deciduous leaves have distinct teeth and are approximately 3 to 6 inches long, and almost as wide, with long, slender stems. In general, American species have larger leaves than European ones. Linden leaves often have fine hairs.
The leaves turn yellow or brown in the fall. American Basswood (Tilia americana) is native to the eastern U.S. Some sources recognize T. carolinia and T. heterophylla as separate species, on the basis of leaf hairiness, but the U.S. Department of Agriculture (USDA) regards them as variants of T. americana. According to the Penn State Extension, “Earlier classifications recognized up to fifteen native [North American] species and thirteen varieties”. I make no distinction. In winter, the leaf buds are distinctly red.
Linden Flowers
In the early summer, after the leaves appear, Basswood produces slender bracts with the flowers that resemble willow leaves. The bracts are yellow-green, and for a few weeks, stand in sharp contrast with the darker green leaves. Attached to the bracts are small round buds that develop into fragrant, pale-yellow flowers with 5 small petals. The flowers attract bees and are thus insect pollinated. Basswood flowers are a significant source of honey, and the trees are known as “Bee Trees” in some areas.
According to the USDA Woody Plant Seed Manual, “The nectar of some species is so overpowering that bees can be found inebriated on the ground beneath the tree”. Kate Bradbury’s The Tree in my Garden says that nectar from Europe’s Silver Linden (Tilia tomentosa) is even poisonous to bees, so the domestic T. americana is the environmentally better choice if you’re planting one.
Linden is monoecious, with perfect flowers. Monoecious trees have male and female flowers on the same tree, and in the case of perfect flowers, male and female parts in the same flower. In contrast, dioecious trees have male and female flowers on separate trees.
Linden flowers become small, spherical fruits that flutter away in autumn, with the bracts serving as parachutes. A few of the distinct fruits usually persist on the tree for several months, making Linden recognizable in the winter. Seed production in Basswoods normally starts at around 15 years and continues to about 100. The trees can live for 200 or more years.
Linden Bark
Linden bark is recognizable, but subtle, and I was able to recognize many other trees by their bark before I could recognize Linden. Several trees have an interlaced pattern, making diamond shapes, including Black Locust, White Ash, some Black Walnut, and Bitternut Hickory. Many more trees have straight furrows. Linden bark is somewhere between the two.
American Basswood reaches a height of 60 to 100 feet, and a diameter of 2 to 3 feet. The Ohio Champion, located in Ross County, has a height of 100 feet, a trunk diameter of 5.4 feet, and crown width of 43 feet.
Identification Summary
Trees with toothed, lopsided heart-shaped leaves, fragrant pale-yellow flowers with slender willow-like bracts that produce small, round, persistent fruits. Small red buds and somewhat crisscross bark in winter.
Similar Trees: The toothed, asymmetrical leaves might resemble those of mulberry, especially Red Mulberry, but the latter usually has at least a few lobed leaves that ooze milky sap when broken, and mulberry trees often bleed dark sap from splits and broken limbs.
Lindens require moist, but well-drained soil, and they tolerate a range of soil types, including rocky and clay-rich soil. American Basswood prefers somewhat alkaline conditions. Lindens do well in full sun, and with their dense foliage, provide excellent shade.
Lucy Braun’s The Woody Plants of Ohio indicates that Tilia americana (which Braun considered to be four different species) is found in nearly every county in Ohio. The Columbus, Ohio Street Tree Inventory lists three species of Linden, with the following percentages of occurrence on city streets: Littleleaf Linden (Tilia cordata) 3.71%, American Basswood (T. americana) 1.49%, and Silverleaf Linden (T. tomentosa) 0.58%, ranking 7th, 18th, and 41st, respectively. Only T. americana is native.
American Basswood lumber has a Janka hardness of 410 lbf and a density of 0.42 g/cc, according to the Wood Database, compared to the median in my list of 73 Ohio trees of 1,075 lbf and 0.64 g/cc. (My list of trees is admittedly somewhat arbitrary and not weighted in any scientifically rigorous way). This hardness is lower than that of many so-called softwoods, and less than half that of Eastern Redcedar.
Uses of Linden Wood
Basswood’s softness, uniform light color, and lack of strong grain make it ideal for carving. Wood Database also lists, “….. lumber, musical instruments (electric guitar bodies), veneer, plywood, and wood pulp/fiber products” as applications for Linden wood. Other uses include boxes, wooden toys, Venetian blinds, artist’s charcoal, and yardsticks. Like Ohio Buckeye, Basswood’s light weight made it suitable for prosthetic limbs in earlier times.
In Europe, Linden’s tendency to sprout from stumps made it a common choice for coppicing. The trees were cut down, and the emerging sprouts were fed to cattle as “tree hay”. Coppiced stumps were sometimes maintained for hundreds of years. The slender twigs, or wythes of various species were made into baskets, woven walls and fences, light furniture, and other objects. Trees were also coppiced at 25-year intervals to provide a sustainable source of lumber and fuel. Until the introduction of Chinese hemp in the fifth century, the inner bark, or bast, was a significant source of cordage in Europe.
A novel use of Basswood discovered by the University of British Columbia is in the production of Nxylon. Nxylon is an ultra-black material made by blasting Linden wood with high-energy plasma beams. The material absorbs 99% of light, compared to the 97.5% absorbed by black paint. The extreme darkness is useful for the inner linings of telescope tubes and other optical devices in which reflections are undesirable. Other uses include the manufacture of watch faces and jewelry traditionally made from onyx or ebony.
The Native American Ethnobotany Database lists numerous uses of Tilia americana bast for cordage to make rope, baskets, nets, clothing, bags, mats, and shoes. The wood was used for fuel, furniture, and carved objects. Many tribes also used Linden for medicinal purposes, including:
- Hawaiian (tribe not specified) – substance from inner bark given for pain during childbirth. Inner bark or flowers used as a laxative. Liquid from bark used for chest congestion.
- Algonquin – Infusion of leaves used as an eyewash.
- Cherokee – Used inner bark used to treat dysentery. A jelly was made from some part of the tree to treat coughs. A decoction of bark mixed with cornmeal was used as poultice for boils. A decoction of inner bark and twigs was used during pregnancy for gastrointestinal problems. Bark from a tree struck by lightning was chewed and spat on snakebites.
- Iroquois – An infusion of bark was used to increase urination. A decoction was taken to induce vomiting during the early stages of tuberculosis. A poultice of leaves was applied to broken-bone injuries. A decoction of branches was used as wash for babies that didn’t walk early enough.
- Malecite – An infusion of roots or bark was used to eliminate worms.
- Meskwaki – A poultice of inner bark was applied to cause boils to open.
- Micmac – A decoction from roots was used for worms.
And finally, the Chippewa ate young twigs and buds, cooked or raw.
Linden leaves, especially when young, and flowers are edible. Linden sap can be drunk as is, or boiled to make a sweet syrup.
Linden flowers are used to treat respiratory problems, high blood pressure, and headaches. They are also used to increase urine production and to reduce muscle spasms in the digestive tract. Linden charcoal was, and is used to treat digestive problems, and it’s used on the skin to treat infections and burns.
The German word, “lindern”, meaning to soothe, is derived from the Linden tree. But according to Laura C. Martin’s The Folklore of Trees & Shrubs, “Scientists warn that protracted use of tea made from the flowers may be harmful, causing damage to the heart”. Of course, the correct dosage is important for all medicines.
Illinois Wildflowers includes the following faunal associates for Tilia americana:
- For nectar or pollen – honeybees, bumblebees, wasps, blow flies, and various moths,
- Destructive consumption – wood-boring long-horned beetle larvae, leaf beetles, gall-fly larvae, aphids, leafhoppers, moth larvae, walkingsticks, and spider mites, and
- Elk and deer browse on leaves and twigs, rabbits feed on sapling bark, and ground squirrels eat the seeds.
Additionally, Lindens, like many light-colored woods, tend to hollow out and provide habitats for many animals.
The Linden in Mythology
In Germanic and Norse countries, Linden was associated with the goddess of love, Freya. Young people danced around the Lindens, and women hoping to give birth hung votive offerings in their branches. Renaissance wood carvers in Germany carved Linden wood into countless statues and religious icons.
Because the tree was associated with healing and health, a woman’s prayers to a statue of the Virgin Mary carved of Linden was believed to offer special protection. But after dark, Lindens were best avoided, since they attracted fairies, elves, and dragons.
In ancient Germany, magistrates considered Linden a tree of wisdom, and they made decisions and pronouncements under Linden limbs. Trials were also held beneath Lindens, because it was believed that one could not tell a lie beneath them.
Alice Thoms Vitale’s Leaves in Myth, Magic & Medicine tells us that, “In Scythia, an ancient country north of the Black Sea, local soothsayers twined Linden leaves around their fingers while uttering prophesies, claiming the the tree spoke to them through their leaves”.
Ovid’s ancient work, Metamorphoses, recounts the story of Baucis and Philemon. The gods Jupiter and Mercury disguised themselves as poor travelers, and wandered the streets of Phrygia. No one but Baucis and Philemon offered them food and rest. The gods punished the people of Phygria, sparing Baucis and Philemon’s home, and turned their humble dwelling into a palace, where they spent their remaining lives. At the end of their lives, Baucis and Philemon were turned into Linden and Oak trees growing from a single trunk. (Linden was the female, and oak the male, in case you were wondering). Ever since, Linden has been a symbol of love, fidelity, and hospitality.
According to Simon Wills’ A History of Trees, the ancient Romans made their shields out of Linden. While the wood isn’t very hard, its softness let it absorb the blow of arrows, and its light weight made it easy to carry and use.
Linden as a Surname
The Swedish botanist & zoologist, Carl Linnaeus, who established our standard classification scheme of family, genus, species, etc., and who named the genus Tilia in 1753, had a personal connection to the linden tree. His father, Nils Ingemarsson, needed an official surname to enter the university, and adopted the surname “Linnaeus” from the Latin for linden, after a huge tree that grew near the family estate. Remember this giant of science when you walk beneath a Linden tree – preferably before dark!
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Further Information
You can also listen to my talks on Ohio Broadleaf Tree Identification on YouTube, Part 1 and Part 2.
