Southwest Desert Flora

The Rutaceae or Rue Family is a medium to large size family of flowering plants belonging to the order Sapindales. The order Sapindales includes 2 other relatively significant North American families including Sapindaceae or soapberry family with 27 genera, and Anacardiaceae or sumac family with 22 genera. Some of the largest genera include Zanthoxylum, Melicope, Agathosma and Boronia.

World-wide the Rutaceae family has more than 150 genera and approximately 1,700 species while in North America there are approximately 40 genera and 155 taxa overall. Family members are made up of shrubs, trees and a few herb/forbs and are distributed primarily in tropical and warm temperate areas. The greatest diversity of the family occurs in southern Africa and Australia.

Common characteristics: In Rutaceae, most species have organs with glandular dots containing aromatic oils (pellucid); often fragrant flowers; spines and winged petioles. Leaves: alternate, opposite or whorled, 1 to 3 foliate, simple or palmately or pinnately compound, leaves sometimes reduced to spines; stipules absent, leaves mostly evergreen. Flowers: mostly bisexual (perfect) or sometimes unisexual, showy, usually with strong scent, flowers producing nectar; actinomorphic or sometimes zygomorphic; flowers (corolla and calyx) commonly divided into four or five parts, flowers attract insects such as small flies and bees. Inflorescence: terminal or axillary in racemes, cymes, spikes, and other types. Fruit: variable, capsules, follicles, drupes, berries (citrus fruit is a modified berry), samaras and schizocarps, seeds 1-2 to many per carpel.

Plants of economic importance: The most important genus in the Rutaceae family is Citrus which includes Oranges, Lemons, Limes, Grapefruits, Tangerines, Kumquats and more. Ornamentals are mostly from temperate regions and are popularly used as hedges and for attractive flowers and red berries; other species are used in the perfume industry.

The Rutaceae is not a significant family in the southwest. Ptelea and Thamnosoma are each well represented with large populations as is Choisya to a much lesser extent. Zanthoxylum is widely represented east of the Mississippi River.