Identifying characteristics:
Also called the American linden, this species is a tall (60- to 80-foot),
stately, straight-trunked tree with slender, spreading, low-hung branches.
It characteristically sprouts from the base to form a clump of several trunks
surrounding a hollow, declining older tree. Young trees are pyramidal, becoming
ovate to rounded with branches that droop down then up. The broad, ovate
leaves are simple, alternate and 3 to
8 inches long, with toothed margins. The leaf base is heart-shaped and unequal.
The upper surface is smooth and dull green, the lower surface paler with
tufts of hair in the vein axils. Autumn leaves are green or yellow-green,
sometimes developing a brownish cast after a particularly dry summer. The
fragrant, creamy-yellow flowers
are 0.5 inches wide, produced in open, pendulous clusters 6 to 8 weeks after
the leaves have appeared. Each inflorescence hangs from a stalk on a 3-
to 4-inch-long, narrow, leaflike bract that persists with the fruit. The
fruits are roundish, dry drupes coated
with dense, woolly, brownish hairs. Fruit crops are usually heavy each year,
ripening in the fall and often persisting on the tree into winter. The small,
half-elliptic leaf scars have numerous bundle scars. Buds
are broad, flattened and lopsided, with 2 or 3 reddish, overlapping visible
scales. A terminal bud is absent. The grayish-brown bark
is furrowed into narrow, scaly ridges.
Similar species:
- red mulberry (Morus rubra)
- little-leaf linden (T. cordata)
Ecology:
Distribution: The basswood is native from Canada to North Carolina,
west to Oklahoma, Kansas and North Dakota. The only native linden in Iowa,
it occurs throughout the state.
Habitat: This species has a deep, wide-spreading root system and, although it prefers deep, moist, fertile soil, it will grow on drier, gravelly soils. In Iowa it is found on sheltered, north- and east-facing slopes of stream valleys, often becoming the dominant species in moist, upland woods. The basswood tolerates shade, especially when young, is pH tolerant and is not particularly tolerant of air pollution. Lindens are usually pest- and disease-free but borers, scale, linden mites, leaf-eating insects and some minor leaf spots may be problematic. The thin bark of young trees makes them susceptible to sunscald, mower injury and frost-cracking.
Uses:
Wood: The common name refers to the use Native Americans made of
the tough, fibrous inner bark, or "bast." The pioneers called
the tree "bastwood," and later "basswood." The bark
was soaked in water, allowing the non-fibrous portions to rot, then twisted
into ropes, cords and thongs. It is a major timber tree in the Great Lakes
states. The wood is pale, light, soft and easily worked. It is a
favorite wood for carving and is also used for boxes, crates, barrels, venetian
blinds, veneer, musical instruments, yardsticks and inner parts of furniture.
Because it is cheap and abundant, it is a source of paper pulp. The wood
imparts no flavor and is used in the apiary industry for honey combs and
other supplies.
Wildlife: The fragrant flowers attract bees and the nectar provides a distinctively-flavored honey. Old hollow trees provide shelter for bees and other animals. The seeds are less important to wildlife than those of many other native trees, but are eaten by quail, squirrels and rodents. Rabbits are the most serious animal pest, cropping the young trees as they emerge from suckers, and deer feed on the twigs and foliage.
Horticulture: Large size limits the use of this species in the landscape, although it is a fast-grower and a good shade tree. This species is perhaps best left in its natural setting or used only in large areas like parks and golf courses. Decaying leaves of the basswood release quantities of nitrogen, calcium, phosphorus and potassium, making this an important soil-improver in the forest. Cultivars include 'Redmond,' a dense, pyramidal form with large leaves, but slow to establish; and 'Rosehill,' a fast-grower with an open crown. In Iowa, various European species are planted as ornamentals. The little-leaf linden (T. cordata), though it grows slower, is smaller and more desirable as an ornamental than the basswood.
