A genus of about 150-175 species of shrubs or (in a few species) small trees that were previously included in the family Caprifoliaceae. Recent classifications, based on molecular phylogeny, put them in the family Adoxaceae.

They are native throughout the temperate Northern Hemisphere, with a few species extending into tropical montane regions in South America and southeast Asia. In Africa, the genus is confined to the Atlas Mountains.

The leaves are opposite, simple, and entire, toothed or lobed; cool temperate species are deciduous, while most of the warm temperate species are evergreen. Some species are densely hairy on the shoots and leaves, with star-shaped hairs.

The flowers are produced in corymbs 5-15 cm across, each flower white to cream or pink, small, 3-5 mm across, with five petals, strongly fragrant in some species. The gynoecium has 3 connate carpels with the nectary on top of the gynoecium. Some species also have a fringe of large, showy sterile flowers round the perimeter of the corymb to act as a pollinator target.

from: Wikipedia