Fig. 20. — Basswood (Tilia americana). Photographed by Lovell.

from New Brunswick to Nebraska and Texas, and especially abundant in the Alleghanies. T. Michauxii extends from Connecticut to Florida and Texas; and T. heterophylla from Pennsylvania to southern Illinois and Alabama, but is most common in limestone regions. The three species may be separated by the following leaf characters: T. americana has the leaves smooth on both sides; in T. Michauxii the leaves are smooth above and pubescent or woolly beneath; and in T. heterophylla