The Rutaceae are a family, commonly known as the rue or citrus family, of flowering plants, usually placed in the order Sapindales.
Species of the family generally have flowers that divide into four or five parts, usually with strong scents. They range in form and size from herbs to shrubs and large trees.
The most economically important genus in the family is Citrus, which includes the orange (C. × sinensis), lemon (C. × limon), grapefruit (C. × paradisi), and lime (various, mostly C. aurantifolia, the key lime). Boronia is a large Australian genus, some members of which are plants with highly fragrant flowers and are used in commercial oil production. Other large genera include Zanthoxylum, Melicope, and Agathosma. About 160 genera are in the family Rutaceae.
Most species are trees or shrubs, a few are herbs (Boenninghausenia and Dictamnus), frequently aromatic with glands on the leaves, sometimes with thorns. The leaves are usually opposed and compound, and without stipules. Pellucid glands, a type of oil gland, are found in the leaves responsible for the aromatic smell of the family's members; traditionally they have been the primary synapomorphic characteristic to identify the Rutaceae.
Flowers are bractless, solitary or in cyme, rarely in raceme, and mainly pollinated by insects. They are radially or (rarely) laterally symmetric, and generally hermaphroditic. They have four or five petals and sepals, sometimes three, mostly separate, eight to ten stamen (five in Skimmia, many in Citrus), usually separate or in several groups. Usually a single stigma with 2 to 5 united carpels, sometimes ovaries separate but styles combined.
The fruit of the Rutaceae are very variable: berries, drupes, hesperidia, samaras, capsules, and follicles all occur. Seed number also varies widely.