Thamnosma montana
Turpentine broom
Photo by Chez Brungraber
Family: Rutaceae · Type: Subshrub · Native
Thamnosma montana (Turpentine broom) is a native California subshrub in the Rutaceae family, recognized by Only representative of Rutaceae in California deserts, distinct from coastal citrus family members.
Turpentine broom is a California native shrub found in the Peninsular Ranges and Desert bioregions on dry slopes, washes, and mesa tops at elevations below 2,100 meters. Flowering from February to May, this plant produces dark purple flowers with elliptic petals 8 to 12 millimeters long with reflexed tips. Growing 3 to 6 decimeters tall with a distinctive broom-like form, the shrub has yellow-green stems that are densely gland-dotted and generally leafless. Its simple leaves are small, measuring 0.5 to 1.5 centimeters long. The fruit develops with lobes approximately 5 millimeters wide, containing 1 to 4 reniform seeds per chamber.
Identification and appearance
Key characters: Only representative of Rutaceae in California deserts, distinct from coastal citrus family members
Habitat and range
Habitat: dry slopes, washes, mesa tops
Elevation: < 2100 m
California counties: San Bernardino, Riverside, Inyo, Imperial, San Diego, Los Angeles, Kern
Outside California: to Utah, Arizona, Mexico
Bloom period
Thamnosma montana blooms Feb-May.
How to tell it apart
vs Ephedra: Thamnosma has dark purple flowers and turpentine scent; Ephedra has tiny scale-like leaves, jointed stems, and no strong scent.; vs Senna: Thamnosma has simple alternate leaves and purple flowers; Senna has compound leaves and bright yellow pea-like flowers.; vs Scutellaria: Thamnosma has simple alternate leaves and strong turpentine scent; Scutellaria has opposite leaves and no resinous odor.; vs Psorodendron: Thamnosma has simple leaves and dark purple flowers; Psorodendron has compound leaves and yellow pea-flowers.; vs Gutierrezia: Thamnosma has sparse alternate leaves and purple flowers; Gutierrezia has needle-like leaves and yellow composite flower heads.
Frequently asked questions
Is Thamnosma montana native to California?
Yes. Thamnosma montana is native to California (recorded as native).
When does Thamnosma montana bloom?
Thamnosma montana blooms Feb-May.
Where in California does Thamnosma montana grow?
Thamnosma montana occurs in San Bernardino, Riverside, Inyo, Imperial, San Diego, Los Angeles, Kern, at elevations of < 2100 m.
What plant family does Thamnosma montana belong to?
Thamnosma montana is in the Rutaceae family, genus Thamnosma.
What habitat does Thamnosma montana grow in?
Thamnosma montana grows in dry slopes, washes, mesa tops.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.