Southwestern San Diego County into northern Baja California .
Twenty-three occurrences on conserved lands in MUs 3 (Crestridge Ecological Reserve, Marron Valley Mitigation Bank, Otay Lakes Cornerstone Lands, Mount Miguel Open Space, San Diego National Wildlife Refuge, Otay Ranch Preserve, Otay Mountain Ecological Reserve, Oneal Canyon Preserve, Rancho Jamul Ecological Reserve) , 4 (Mission Trails Regional Park, Rattlesnake Mountain, San Vicente Highlands Open Space Preserve), and 6 (Los Penasquitos Canyon Preserve, San Diego National Wildlife Refuge, Escondido Creek Preserve, Rancho La Costa Habitat Conservation Area).
Elevation range is 50-465 meters . Found in clay soils in chaparral, coastal scrub, valley and foothill grasslands, and vernal pool habitats.
Themidaceae family . Previously Muilla clevelandii.
Perennial bulbiferous herb .
Bloom period is April-May .
Threatened by urbanization, road construction, vehicles, nonnative plants, and illegal dumping .