Well, there is a shrub that can be seen growing predominately throughout the desert southwest that releases a wonderful fragrance whenever it rains. This shrub is known as creosote (Larrea tridentata).
This characteristic desert shrub can be found growing in the California desert, the southern third of Arizona, New Mexico and the western half of Texas otherwise known as the Mojave, Sonoran, and Chihuahuan deserts.
I am a bit of a science geek and what I find fascinating is that creosote shrubs are classified as a single species, but depending on what desert they are growing in, have different chromosome numbers. Those found in Texas have 26 pairs, while in Arizona they have 52 pairs and in California they have 78 pairs. Some scientists theorize that the creosote found in California evolved from those in the Arizona desert and the higher chromosome count somehow enabled them to survive the drier conditions of the Mojave desert.
Believe it or not, some colonies in the Mojave desert are over 11,500 years old.
Their small leaves are covered with resin to protect against water loss and from being eaten. It is widely thought that creosote produces a toxin or uses up all available water to keep other plants from growing close by therefore keeping competition for limited resources to a minimum.
I had a client who had a large beautiful creosote growing in their garden and had a boxwood hedge that was thriving, except for one area where a few boxwood shrubs were yellow and sickly. They had been that way for years. Coincidentally those sickly shrubs were a few feet away from the creosote.
Creosote can be grown in the desert landscape under 5,000 ft. They do best with limited water and grow slowly. In their native habitat, they typically grow to 4 feet in height, but in a landscape setting, they can reach heights of up to 12 feet.
To start from seed, pour boiling water over the seeds and let sit overnight. Then plant in soil and water. As the plant grows, slowly taper off the water. I recommend only watering a mature creosote, to a depth of 2 feet, 2 to 3 times in the summer, but they can survive without any supplemental water.
**Here is an interesting fact - did you know that you don't have to wait for it to rain to enjoy the fragrance of this shrub? All you need to do is take a few leaves from the creosote and rub them between your fingers and you'll be able to smell the refreshing scent of rain that is so characteristic of the Southwest.