Most rutaceae (rue family) species are trees or shrubs, inhabiting desert or tropical regions, so in the US they are most common in Arizona, California, Texas and Florida. Leaves are usually compound - palmate or pinnate, the flowers have four or five petals, and fruits are variable, though they are often large and sweet; the most well known genus is citrus, which includes the oranges, lemons and grapefruits. Only a few genera contain species native to the western US, including amyris, choisya, ptelea and thamnosma.