Citrus, genus of plants belonging to the rue family (Rutaceae), and yielding pulpy fruits covered with fairly thick skins. Economically important plants in this group include the lemon (C. ×limon), lime (C. ×aurantiifolia), sweet orange (C. ×sinensis), sour orange (C. ×aurantium), tangerine (C. reticulata), grapefruit (C. ×paradisi), citron (C. medica), and shaddock (C. maxima).
