San Diego Management & Monitoring Program

Santa Rosa basalt brodiaea
Brodiaea santarosae

Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Southwest Riverside County and immediately adjacent Miller Mountain in San Diego County [1]. Smallest range of the southern California Brodiaeas, with just four known populations occupying only a small portion of a 40 km2 area, plus a fifth small population disjunct by 11 km.

Known Populations in San Diego County

Three occurrences on Conserved Lands in MU8 (Cleveland National Forest).

List status

None [2].

Habitat affinities

Occurs only on or very close to the 8–11 million-year-old Santa Rosa Basalt [1]. Grows in many habitats, including next to vernal pools, but can also grow in drier locations. Can grow in disturbed areas, disturbed soils, on top of the water pipes, and in roadside berms. Elevation range 565-1045 meters [2].

Taxonomy and genetics

New species of Brodiaea previously collected by at least six different botanists and variously determined as B. orcuttii (E. Greene) Baker, B. filifolia (S. Watson), or a hybrid between the two [1]. Analysis distinguished it from B. filifolia and B. orcuttii by at least 11 separate characteristics. In the Themidaceae family [2].

Life history demography

Perennial bulbiferous herb [2] and basalt endemic [1].

Seasonal phenology

Blooming period is May-June [2]. Seeds mature in late spring and early summer.

Pollination seed dispersal

Often reproduce by corms with populations in small areas often being clonal [1].


There appears to be low threat from humans [1] with possible threats from development [2]. Long-term threat is the erosion of the Santa Rosa Basalt and loss of native habitat [1]. Forms sterile hybrids with B. terrestris ssp. kernensis [2].

Special considerations:

Appears to exist stably with the abundant nonnative grasses that are found at a few of the sites [1]. Four of the known populations are protected as part of the Santa Rosa Plateau Ecological Reserve and Cleveland National Forest. The large population on Avenaloca Mesa is partially protected by the Nature Conservancy.

Santa Rosa basalt brodiaea sources