Turpentine Broom

In March while exploring near the Eureka Mine in Death Valley National Park CA, I came upon a small patch of turpentine broom (or turpentinebroom). A native, long-lived shrub, turpentine broom (Thamnosma montana) grows on gravelly or rocky slopes and mesas, mostly from 2,000 to 4,000 feet. It can be found in the southern deserts of California, Nevada, Utah and Arizona and into Northern Mexico.

The entire shrub is covered in small, warty (blisterlike) glands that secrete aromatic oils. The plant is not hairy, nor does it have thorns. The profusely branched, yellow-green stems arise from a root stock. Turpentine broom stems are stout, spine tipped and can photosynthesize.

The leaves of this Citrus (or Rue) Family (Rutaceae) member are deciduous and are usually seen only before flowering or after rains. Turpentine broom leaves are alternate, simple and linear.

Turpentine broom flowers are such a deep purple they almost look black. Occurring at intervals along the stems, the flowers have four green sepals. The four petals curve slightly outward at the tips revealing a long stigma and eight shorter, yellow-tipped stamens. The ovary is superior.

The persistent fruits are leathery, stalked capsules that have two lobes resembling joined spheres. Even the light tan capsules have aromatic warts. The seeds are pale and kidney-shaped.

Native Americans employed turpentine broom in ceremonial capacities, for pest control and in medicine. Preparations of this plants were believed to heal wounds.

The genus name, Thamnosma, means odorous shrub in Greek. The specific epithet, montana, refers to mountains in Latin. Another common name for T montana is Mojave desert rue.

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