About 23 species, North America, Europe, Asia, Africa.

As traditionally circumscribed, the family Tiliaceae comprised about 450 species grouped into about 50 genera. Molecular studies have shown that these genera are not a natural lineage, with various groups of genera more closely related to different components of the order Malvales (C. Bayer et al., 1999; Alverson et al., 1999; Whitlock et al., 2001). There are only two genera of trees supported by the DNA sequence data as close relatives of Tilia: Craigia W.W. Sm. & W.E. Evans (two species of southern China and Vietnam) and Mortoniodendron Standl. & Steyerm. (twelve species from Mexico to northern South America).

Species of Tilia are often grown as shade trees. In addition to the native species, the most commonly encountered species in cultivation in the Midwest is T. cordata Mill. (small-leaved linden), which produces flowers lacking staminodes, has generally smaller leaves (usually less than 10 cm long), produces axillary tufts of short hairs in the leaf axils, and has nuts with a relatively thin shell. Several other species are occasionally cultivated as specimen plants.

The light wood of Tilia species has been used for furniture, veneers, plywood, crates, musical instruments, utensils, and crafts, and as pulp for paper. The fibrous inner bark was harvested by Native Americans to make rope and twine (Steyermark, 1963). The flowers often have a distinctive fragrance that has been described as sweet and peppery, and can be used to make an herbal tea. They are popular as a pollen source for honey-bees. The leaves and fruits provide food for wildlife.

G. J. Anderson (1976) studied the breeding system and pollination biology of Tilia species in North America. He concluded that the flowers are outcrossing, with the stamens shedding pollen before the stigmas become receptive. The biochemically complex fragrances of the flowers become stronger and more pungent as evening approaches. The flowers appear to lack pollinator specificity and can be pollinated by a variety of bees, wasps, butterflies, skippers, and flies during the day, as well as nocturnally by moths.