by Karen Howe, Native Plants Class 2003
Common names: Creosote, chaparral, greasewood
Family: Zygophyllaceae
Synonomy: Larrea mexicana Moric.
Etymology: The genus refers to Don Juan Antonio Hernandez Perez de Larrea (1730-1803), a Spanish clergyman and benefactor to the sciences (1).

Identification
Growth form: Creosote is a clonal shrub that grows 1-2 or 3 m high. Is considered the longest-living plant with some clones ~10,000 years old (1).
Roots: Roots are generally fibrous and shallow and may penetrate only 170 cm but extend outward 4 m. Depending on soil conditions, the root system can extend laterally and vertically (3).
Stem: The woody stems of creosote arise at an angle from the ground or vertically from the base or from lower branches (3)
Leaves: Pinnate with 2 narrowly elongated leaflets joined at the base attached directly to the stem. Leaflets are thick, resinous and strongly scented.
Inflorescence/flowers: Solitary and axillary, petals are yellow (1)
Fruit: A schizocarp that splits into 5 mericarps, each containing a single “boomerang” shaped seed (2).
Similar species: A variety of L. tridentata, var. arenaria, occurs in sand dunes in Southern California (2).

Ecology
Life history: Perennial shrub.
Native/introduced: Native to arid and semi-arid regions of Southwestern United States and Argentina, Bolivia, Chile, Mexico and Peru (2)
Photosynthetic pathway: C3
Phenology: The growing season for creosote is typically April-May, but can be locally variable due to runoff availability. Flowering is thought to be moisture and temperature dependent (2)
Distribution: Bajadas, gentle slopes, valley floors, sand dunes, and arroyos at elevations up to 1515m and in calcareous, sandy soil and alluvial soils, often underlain by caliche. Found in Cochise, Coconino, Mohave, Greenlee, Santa Cruz, Pima, and Yuma counties in Arizona. Occurs in desert communities from California west to Texas, from Utah south to North-Central Mexico (3,4)

Uses
Native Americans use boiled leaves in a tea for medicinal purposes such as cold remedies, analgesic, orthopedic aid and as a general tonic for ill-health (4). Pima Indians have also used tea for treatment of diabetes (5). Lac produced by insect, Tachardiella larrea, used to fix arrow points, to make awl handles in basketry, and as a sealant on pottery (4,5). Other uses include tattooing, tools, and fiber (4). Can be found marketed as “chaparral” tea (6).