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Tilia americana L. American basswood

Leaf showing the cordate (roundly indented) base and typical venation

Also known as: American linden.

Habitat

In New Brunswick, basswood occurs only in the west and southwest, but principally in the St. John River valley. It grows as a scattered tree on rich, moist sites in mixture with many other species, mostly hardwoods. It tolerates shade.

Form

Mature tree

Basswood can grow to heights of up to 27 m and to stem diameters of up to 75 cm. The stems are usually straight and distinct into the upper parts of the even, rounded, rather small crowns. The branches tend to arch outwards with upturned ends.

Morphology

The leaves are deciduous, simple, and alternately arranged. They are 12–15 cm long and almost as wide, and have petioles, which are often angled away from, and one-third to half as long as, the laminae. The leaves are broadly ovate, tapered to a pointed tip and cordate (roundly indented) at the base, which is often unequal from one side to the other. The leaf margins are coarsely toothed, and there are tufts of hairs on the under surfaces where veins meet.

Twig with pseudo-
terminal and protruding lateral buds

The twigs are moderately stout, green to purplish brown or yellowish brown, and somewhat zigzagged. The buds are reddish, plump, and lopsided with two or three overlapping scales visible, and are offset from their leaf scars below. The end bud is pseudo terminal, and is usually angled over the twig end away from its leaf scar. Leaf scars are semi-oval and have five to ten tiny vein scars.

Flower buds borne in a cluster from a pale green bract

The flowers bloom in midsummer after the leaves have fully expanded. They are borne in small, branched, hanging clusters that are carried by a single stem that grows from the midrib of a linear-lanceolate pale yellow-green bract that is about 7 cm long. From each flower in the cluster, a hard nut-like fruit about 6 mm in diameter, can develop, and can contain a single seed. When the fruits are ripe in early fall, the whole bracted structure may be shed and whirl to the ground. This starts to happen at about the time of leaf fall, but some fruits may be held on the trees over winter.

Fruits borne clustered below a pale brown mature bract

The bark is greyish green whenyoung, and greyish brown with long, narrow, fairly smooth- surfaced ridges when old.

Bark of stem 33 cm in diameter

Notes

Basswood has diffuse-porous wood, light in both weight and color, soft, and uniform. These features make it valuable for hand carving, modeling, turnery, interior trim, and piano keys. The flowers are noticeably fragrant, and basswood honey has a distinctive taste. Rope can be made from fibers in the bark. This fibrous feature is the reason that squirrels strip bark from thin branches and take it to line their drays.