Tilia species are mostly large, deciduous trees, reaching typically 20 to 40 m tall. As with elms, the exact number of species is uncertain, as many of the species can hybridise readily, both in the wild and in cultivation. They are hermaphroditic, having perfect flowers with both male and female parts, pollinated by insects.

The trunk is stout, with pale grey to brownish-grey bark, smooth at first, becoming coarsely fissured or scaly on older trees; the inner bark, called 'bast', is soft, but fibrous, with high tensile strength. The wood is white, fairly soft, with minimal wood grain, making it popular for wood carving.

The leaves of Tilia species are heart-shaped, and most are asymmetrical, with oblique-cordate (heart-shaped) leaves 4 to 20 cm across, sometimes more, to 25 cm in the hybrid cultivar Tilia 'Moltkei'. In all species, the leaf margin is toothed, sometimes markedly so, with T. henryana having conspicuous long bristle-like teeth up to 4.4 mm long. In another species, T. mongolica, the leaves are also distinctly three- to five-lobed as one or two pairs of the marginal teeth are larger than the others; in this species, the leaf base is also usually symmetrical, not oblique as in other limes.

The flowers are small (10–15 mm diameter), symmetrical, with five sepals and five petals, the petals yellow to greenish-yellow, about twice the length of the sepals when fully open; they are strongly scented, and very attractive to bees and other insects. The flowers of European and American Tilia species are similar, except the American ones bear a petal-like scale among their stamens and the European species are devoid of these appendages. The tiny, pea-sized fruit hangs attached to a ribbon-like, greenish-yellow bract whose apparent purpose is to aid the ripened seed clusters to blow in wind to a little beyond the parent tree. The fruit is mostly smooth and variably downy, but in T. chinensis and T. platyphyllos is prominently ribbed, with five ribs. All of the Tilia species may be propagated by cuttings and grafting, as well as by seed. They grow rapidly in rich soil but are subject to damage by several insects. Tilia is notoriously difficult to propagate from seed unless collected fresh in autumn; if allowed to dry, the seeds go into deep dormancy and take 18 months to germinate.