Any of about 30 species of fragrant northern spring-flowering garden shrubs and small trees that make up the genus Syringa in the olive family, native to eastern Europe and temperate Asia.
Lilacs have deep green leaves and large, oval clusters of compound blooms coloured deep purple, lavender, blue, red, pink, white, or creamy yellow; they are often highly fragrant. The common lilac ( S. vulgaris ) reaches 20 ft (6 m) in height and produces many suckers (shoots from the stem or root). The name syringa was formerly used for the mock orange of the saxifrage family, and the butterfly bush (see buddleia ) is commonly called "summer lilac."