While visiting Sweetwater Creek State Park near where I live, I found myself drawn to the heart-shaped leaves of several basswood trees. These trees are found in scattered areas around the Georgia piedmont region, which includes Atlanta, and I enjoy seeing them. There is much that can be learned about this attractive tree.
Basswood ranges from southern New Brunswick and Maine south to Florida, and west to Manitoba and Texas. It is also found in Mexico. Many are found in the Appalachian forest, where it is often the dominant tree species. Most authorities list four basswood species as native to the North American continent: Tilia americana, found in the north extending into Canada; Tilia heterophylla, found in the Appalachians and piedmont; Tilia caroliniana, found in the coastal plain; Tilia Mexicana, found in Mexico. However, it has been found that the features used to distinguish these four species from one another vary not with genetics but with sun exposure, rainfall, and temperature range. These species are in fact a single species, Tilia Americana. Basswood prefers full sun and loose, rich, moist, and well-drained soil, but will tolerate partial shade and poorer soils with a wide range of pH. It will not tolerate very wet or very dry conditions.
Tilia americana is known in North America as basswood, white basswood, bast, American linden, bass, linn, and beetree. The name bass is derived from the word bast, which is the tree’s inner fibrous bark that has been used to make rope and clothing. The name beetree came from the tree’s extensive use by bees for honey production. In England, the common names for Tilia europaea are limes and linden. Lime is an altered form of the Old English word lind or linde, and the German lind, which means ”lenient, yielding”. This is most likely a reference to how the tree’s leaves take various forms, making identification difficult. It appears there is no confusion in England between the lime and the tree of the lime fruit, probably since no lime fruit grows there.
Trees grow straight, at a medium rate. Many live longer than 200 years. They can grow 100 or more feet tall, and trunks may be more than 3 feet in diameter. An Atlanta Champion basswood in Fernbank Forest was measured to be 128.9 feet tall in 2015. Bark on young trees is smooth and light gray. Older trees develop gray-brown bark with long, flat-topped ridges. Suckers form at the base of trees and also from spreading roots that are frequently defective and less desirable than those grown from seeds. If they are not removed, a clump of small trees will form instead of one large tree. The tree’s large root system can spread 30 or more feet and threaten nearby structures and pipes. The tree is pyramidal in shape when young, and when grown in the open it is more broad than tall, with a rounded and dense canopy. Lower branches are pendulous, but upturned at the ends. Buds are red to green. The tree’s fairly soft wood gives limbs flexibility, which helps them withstand ice and strong wind, but storm damage can occur due to the tree’s narrow crotches.
Leaves on the basswood tree are alternate in arrangement, broadly heart-shaped, and 4 to 8 inches long. There is a short tip at the leaf apex. Leaf size is mostly a function of soil conditions. The leaf base is usually oblique, or not symmetrical. Leaf margins are finely toothed. Tops of leaves are dark green and smooth, and the lower surface is pale green or silvery with a waxy powder that can be rubbed off. Autumn foliage is green with a brown cast, or yellow.
In flowering season, a constant humming can be heard in the tree from bee activity. Flowers are insect pollinated, not wind pollinated, so there is no danger of seasonal pollen allergies from this tree. Flowers bloom in late June to early July, and they are fragrant and very attractive to bees. Flowers are small, creamy white with 5 petals, and held in loose, drooping clusters of 10 to 20 with a yellow-green leaf-like bract. Perfect flowers have both male and female parts. Fruit are clusters of 6 or so rounded, fuzzy nutlets, .2 inches to .3inches in diameter. Each cluster has a special seed-leaf that retards descent so that the wind can carry it further before it strikes the ground. Seeds fall in winter and spring, and may remain dormant for two to three years before sprouting.
The basswood tree has proven very useful. It is an attractive and fragrant landscape tree for shade or lawn use in large areas, that does not trigger seasonal allergies. The inner bark, or bast, has been used to make rope, baskets, nets, mats and cloth. Wood is light, odorless, and medium soft, but harder than white pine. It is great for making furniture, cabinets, shipping crates, veneer, particleboard, woodenware, pulpwood, blinds and shutters. Acoustic properties of the wood make it popular for use in electric guitars, pianos, wind instruments, and for drum shells. The wood’s fine, light grain makes it a great wood to carve. The aquarium industry uses basswood as an air diffuser. Basswood nectar makes superior honey. The leaves are edible in salads, especially when young. They may also be used to wrap food for cooking in campfires. Flowers have been used to make tea. Syrup can be made from the tree’s sweet sap. Leaf buds and inner bark are edible. Oil has been extracted from linden seeds and used as a substitute for olive oil. Twigs can be hollowed to make tubes for fishing bobbers, drinking straws, and blowing tubes. Herbalists use linden flowers in remedies for colds, cough, fever, infections, inflammation, high blood pressure, migraine, as a diuretic, antispasmotic, and sedative. The wood has had use for liver and gallbladder disorders, and cellulitis. Charcoal made from the wood may be used to treat intestinal disorders and other infirmaries.
Heart-shaped leaves are not the only draw of the basswood. It is not only attractive in the landscape, but useful in very many ways. What is there not to like about this tree?