Castilleja densiflora subsp. obispoensis
San luis obispo owl's-clover, San Luis Obispo Owl's-Clover
Photo: parent species Castilleja densiflora · no rights reserved · CC0
Family: Orobanchaceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Castilleja densiflora subsp. obispoensis (San luis obispo owl's-clover) is a native California herb in the Orobanchaceae family, recognized by cream/pale yellow bracts and corolla +- included.
San luis obispo owl's-clover is a rare (CNPS 1B.2) California native annual found in southern Central Coast region in San Luis Obispo County's coastal grasslands at elevations below 400 meters. Flowering from March to June, this plant produces cream to pale yellow flowers with distinctive bracts that closely match the flower color. Growing in delicate clusters with slender stems, it forms compact inflorescences with flowers whose lower lips widen gradually. Its bracts are cream-colored and closely resemble the flower structure, creating a subtle monochromatic appearance. The flowers have calyxes 8 to 20 millimeters long with corolla teeth approximately 2 millimeters in length.
Identification and appearance
Key characters: 21 sympatric species; distinguished by cream/pale yellow bracts and corolla +- included
Habitat and range
Habitat: Coastal grassland
Elevation: < 400 m
California counties: San Luis Obispo, Santa Barbara, Amador
Bloom period
Castilleja densiflora subsp. obispoensis blooms Mar-Jun.
Conservation status
CNPS 1B.2
How to tell it apart
vs Triphysaria: Castilleja lacks the sharp fold in flower throat; Triphysaria has abrupt crease above lower lip.; vs Trifolium: Castilleja has tubular flowers with colorful bracts; Trifolium has round heads of pea-like flowers and three leaflets.; vs Pedicularis: Castilleja has open forward beak and colorful bracts; Pedicularis has closed hood and fern-like leaves.; vs Orthocarpus: Castilleja has open beak you can see into; Orthocarpus has closed hood covering stamens completely.; vs Epilobium: Castilleja has tubular two-lipped flowers and colorful bracts; Epilobium has four separate petals arranged in cross.
Frequently asked questions
Is Castilleja densiflora subsp. obispoensis native to California?
Yes. Castilleja densiflora subsp. obispoensis is native to California (recorded as native).
When does Castilleja densiflora subsp. obispoensis bloom?
Castilleja densiflora subsp. obispoensis blooms Mar-Jun.
Where in California does Castilleja densiflora subsp. obispoensis grow?
Castilleja densiflora subsp. obispoensis occurs in San Luis Obispo, Santa Barbara, Amador, at elevations of < 400 m.
What plant family does Castilleja densiflora subsp. obispoensis belong to?
Castilleja densiflora subsp. obispoensis is in the Orobanchaceae family, genus Castilleja.
Is Castilleja densiflora subsp. obispoensis rare or endangered?
Castilleja densiflora subsp. obispoensis carries California Rare Plant Rank 1B.2, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-08
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.