genus of plants belonging to the rue family (Rutaceae), and yielding pulpy fruits covered with fairly thick skins. Plants in this group include the lemon (q.v.; C. limon), lime (q.v.; C. aurantifolia), sweet orange (C. sinensis), sour orange (C. aurantium; see orange), tangerine (q.v.; C. reticulata), grapefruit (q.v.; C. paradisi), citron (q.v.; C. medica), and shaddock (q.v.; C. maxima, or C. grandis; pomelo).