Common Name: creosote bush

Duration: Perennial

Nativity: Native

Lifeform: Shrub

General: Aromatic, much branched evergreen shrub up to 3.5 m; with dark, glandular bands at the nodes and densely leafy toward the end of the branches.

Leaves: Opposite and evergreen; each leaf consists of a pair of leaflets united at the base; leaflets are elliptical, 1 cm long, dark green, shiny, and strongly-scented (especially after rain). 

Flowers: Yellow, showy, solitary on pedicels from the leaf axils; with 5 petals 7-11 mm long.

Fruits: Globose capsule splitting into 5 nutlets, covered in white silky hairs.

Ecology: Widespread and common on dry plains and mesas below 5,000 ft (1676 m); flowers any time after adequate rain (minimum 12 mm of precipitation) but mostly flowers February to April.

Distribution: s and c CA, s UT, AZ, NM, TX; south to s MEX, and in S. Amer.

Notes: The most common and widespread shrub in warm deserts of North America, ordinarily untouched by livestock; causes dermatitis in some people. Distinguished by the strong, distinct creosote scent; the paired, dark green, lustrous leaves, 1 cm long; and the yellow flowers followed by globose, white-hairy fruits.

Ethnobotany: Used to treat arthritis and allergies. As a salve it is a strongly antimicrobial and a moderate sunblock.

Etymology: Larrea is named for Bishop Juan Antonio Hernandez Perez de Larrea (1731-1803) in Valladolid, Spain, while tridentata means three-toothed, the appearance of the leaves being three-toothed.

Synonyms: Larrea mexicana, Larrea divaricata subsp. tridentata

Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2015

Larrea tridentata is a resinous woody shrub and one of the most abundant components of North American deserts including the Chihuahuan Desert, and ranges into some of the lowest elevations of the Gila Region. The small paired leaflets, fused at their bases, are not symmetrical. The stipules, at first green, soon become reddish, and secrete copious resin. Stipules at the growing stem enclose and protect the young meristems (growing tip.) After a rain the aroma of terpenes from the wet foliage imparts a magical quality to the crisp desert air. The complex aromatic quality of the foliage has long been appreciated by local people for significant medicinal purposes, including inhalants and poultices, but should not be taken internally due to toxicity. The fruit is densely hairy and is the result of a five carpellate ovary that results in five indehiscent hairy nutlets.