Vascular Plants of North Carolina
Account for American Basswood - Tilia americana   L.
Members of Malvaceae:
Members of Tilia with account distribution info or public map:
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Section 6 » Order Malvales » Family Malvaceae
AuthorL.
DistributionFound throughout the Mountains, and present in most of the Piedmont except apparently absent in the northeastern counties (east of Person and Wake counties). Scattered over the southern half of the Coastal Plain, but absent in the northern half and from the Sandhills proper.

The species is present in most counties in the eastern U.S. and southern Canada, south to central FL and central TX. There is a real gap in the range, owing to the ranges of several varieties, in much of eastern NC, and parts of western TN and northwestern MS.
AbundanceThe collective varieties of the species are generally fairly common to common in the Mountains; fairly common in the western and central Piedmont, but rare to uncommon in the eastern third of the Piedmont. Rare to uncommon and local in the southern Coastal Plain; absent in the northern half. The nominate variety -- T. americana var. americana -- is considered by the NC NHP as a Watch List taxon.
HabitatThis species is found only over rich soil, typically circumneutral forested soils. It is most numerous in cove forests, but in the Piedmont it occurs in Basic Mesic Forests and other rich forested sites (i.e. mafic), usually on slopes or other uplands. In the Coastal Plain, it is mostly found in forests over marl, on bluffs, slopes, shell middens.
See also Habitat Account for Rich Dry-Mesic Hardwood Forests
PhenologyFlowers from May to July, and fruits from July to September.
IdentificationThis species is generally treated now as a single one with several somewhat distinct varieties. Collectively, this is a medium deciduous tree, growing to about 60-70 feet tall in most places, but shorter in the lower Coastal Plain. It is quite a familiar species to people in the Mountains and foothills, but in the eastern half of the state it may take some effort to find it. All forms have large heart-shaped leaves, with fine serrations and a small acuminate tip. The base is cordate and often non-symmetrical (one side larger than the other). The leaves average about 5-6 inches long and nearly as wide. They can be very similar to those of mulberries, especially the native Red Mulberry (Morus rubra), but that species often has one or two large finger-like lobes. The best ways to tell the two genera apart are: 1) basswoods have buds with reddish scales and relatively few scales, whereas mulberries have more typical brown buds with numerous overlapping scales; and 2) basswoods have a fruit consisting of several small berries dangling from a narrow leaf-like structure, whereas mulberries have the familiar “blackberry-like” aggregate fruit. Both species can occur in similar habitats, but the basswood requires very rich forested soil, whereas the mulberry can grow in a greater variety of forested habitats.
Taxonomic CommentsA number of references list three or four species for NC: Tilia americana – rare in the mountains and Piedmont; T. heterophylla – numerous in the mountains and less so in the Piedmont; T. caroliniana – scarce along the southern coast; and T. floridana – scarce to uncommon in the southern Coastal Plain and parts of the Piedmont. Weakley (2018) and NatureServe lump these into a single species, with three varieties (with the latter two included as var. caroliniana).

Other Common Name(s)American Linden. Varietal names are generally Northern Basswood (var. americana), Mountain Basswood or White Basswood (var. heterophylla), and Carolina Basswood or Southern Basswood (var. caroliniana). Florida Basswood is used for var. floridana, which Weakley (2018) includes in var. caroliniana.

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