The Creosote Bush grows in the Southwestern United States and Mexico, mainly in the Sonoran, Chihuahuan, and Mohave deserts.  One would think the Great Basin would be included in its residential habitat, but the elevation of 5,000 ft is too high.  I grew up in Henderson, Nevada where we had lots of these huge shrubs in the desert.  At least to me they were gigantic! I walked through them daily back and forth to elementary school.  Henderson’s elevation is only about 2,000 feet above sea level.  In tracking them on the way to Zion National Park, I found they thinned out considerably about half way from St. George to the park, that being around 3,500 feet above sea level.  

It is quite easy (once one knows what to look for) to find this herb in the field.  Amazingly, the Chihuahuan Desert has documented as many as 8,000 plants in a half-acre area, 4,000 plants per half-acre in the Sonoran Desert, and 1,800 per half-acre in the Mohave Desert (Mabry).  I never thought to count how many plants between my home and school as a little girl, but to my delight there were hundreds of them.

The Chaparral plant is a four to eight foot high evergreen shrub with woody roots.  There is no apparent main branch, but many branches growing from one root system.  The branches and stems are dark green, branches compound with dark green opposite leaves on extremely short petioles; at first observation there appears to be two leaves off the short petiole, however at a closer look it is one leaf very deeply lobed.  The flowers are small (no more than ½ inch) with five separate yellow petals and five separate dark green sepals.  After pollination, the petals twist at a 90-degree angle giving a claw-like look.  There are 10 stamens, and the ovary is superior, having five locules, turning to a round ¼ inch fruit with a mass of white to reddish hairs.  The fruits and flowers are commonly found on the plant at the same time, with “…a single mature shrub [producing] more than 2,000 flowers during the growing season” (Nellessen).  Flowers may produce on the plant at four to six years, but heavy flowering and fruiting generally doesn’t occur until after eight to thirteen years (Nellessen).  According to Barbour, the seeds can be stored for as long as eight years and still have germinability.  The leaves are highly resinous with a very pungent odor, especially after a desert rain shower.

The Larrea Tridentata is from the Zygophyllaceae—Creosote Bush Family.  The main identifier of this type of plant family is that the individual components of the plant are in fives (five sepals, five petals, ten stamens).  The family’s leaves are opposite and usually pinnately divided.