Larrea

Larrea is a genus of flowering plants in the family Zygophyllaceae. It comprises several shrubs and small trees native to the Americas, with the best-known species being Larrea tridentata, commonly called the creosote bush.

Distribution and habitat: Larrea species are found in arid regions of North and South America, especially the southwestern United States and northwestern Mexico, and extending into parts of Chile and Argentina. They typically grow in deserts and dry scrublands, where they are highly adapted to drought and poor soils. In some areas they form extensive clonal stands and are a characteristic component of desert scrub ecosystems.

Description: Plants in the genus are evergreen, resinous shrubs. They have small, aromatic leaves that release a distinctive creosote odor when wet. Flowers are generally small and yellow, and fruit takes the form of dry seed capsules. The morphology can vary among species, but all are adapted to harsh desert conditions and have features that reduce water loss and tolerate heat.

Ecology and chemistry: Larrea species produce nordihydroguaiaretic acid (NDGA), a lignan found in resinous exudates. This chemical has attracted attention for various pharmacological and preservative properties, though its safety and efficacy are subject to regulation and further study. The plants contribute to desert ecology through their deep root systems, resin-rich chemistry, and interactions with other desert organisms.

Uses and significance: Indigenous peoples have used parts of Larrea for medicinal purposes and, in some cultures, for other traditional applications. In modern contexts, NDGA and related compounds derived from Larrea have been studied, but commercial use is limited by safety considerations. The genus is primarily of botanical and ecological interest, illustrating adaptations to extreme aridity.