Horse Valley - W of Brentwood, S of Antioch
| Scientific Name | Notes | Rarity Ranks | Common Name |
|---|---|---|---|
| Blepharizonia plumosa | CNPS-EB: *A2 State CNPS: 1B.1 | big tarplant | |
| Hesperolinon breweri | CNPS-EB: *A2 State CNPS: 1B.2 | Brewer's western flax | |
| Microseris sylvatica | CNPS-EB: *A2 State CNPS: 4.2 | sylvan microseris | |
| Navarretia heterandra | CNPS-EB: *A1 State CNPS: 4.3 | Tehama navarretia | |
| Navarretia nigelliformis subsp. radians | CNPS-EB: *A2 State CNPS: 1B.2 | shining navarretia | |
| Navarretia viscidula | CNPS-EB: A2 | sticky navarretia | |
| Amsinckia grandiflora | CNPS-EB: *A1 State CNPS: 1B.1 FESA Status: FE CESA Status: CE | large-flowered fiddleneck | |
| Atriplex coronata var. coronata | CNPS-EB: *A2 State CNPS: 4.2 | crownscale | |
| Calycadenia multiglandulosa | CNPS-EB: A2 | sticky calycadenia | |
| Downingia insignis | CNPS-EB: A1 | cupped downingia | |
| Eschscholzia caespitosa | CNPS-EB: A1 | tufted poppy | |
| Lasthenia minor | CNPS-EB: A1 | coastal goldfields, woolly goldfields | |
| Microseris acuminata | CNPS-EB: A1 | Sierra Foothills microseris | |
| Navarretia atractyloides | CNPS-EB: A2 | holly-leaved navarretia | |
| Navarretia hamata subsp. parviloba | CNPS-EB: A1 | hooked navarretia | |
| Plagiobothrys humistratus | CNPS-EB: A2 | low popcornflower, dwarf allocarya | |
| Plagiobothrys infectivus | CNPS-EB: A1x | dye popcornflower | |
| Deinandra kelloggii | (formerly Hemizonia k.) | CNPS-EB: B | Kellogg's tarweed |
| Leptosiphon ciliatus | (formerly Linanthus c.) | CNPS-EB: B-PV | whisker brush |
| Tropidocarpum gracile | CNPS-EB: B-PV | slender tropidocarpum | |
| Agoseris heterophylla var. unknown | Agoseris heterophylla split into 2 vars. in 2011 Jepson Manual, need field work to resolve vars. | CNPS-EB: B? | annual agoseris |
| Alopecurus saccatus | CNPS-EB: B | Howell's meadow foxtail | |
| Atriplex argentea var. expansa | CNPS-EB: C | silverscale | |
| Blepharizonia laxa | (formerly B. plumosa ssp. visc | CNPS-EB: B | big tarplant |
| Brodiaea terrestris subsp. terrestris | CNPS-EB: B-PV | dwarf brodiaea | |
| Castilleja rubicundula subsp. lithospermoides | CNPS-EB: B-PV | cream sacs | |
| Delphinium hesperium subsp. hesperium | CNPS-EB: B | western larkspur | |
| Deschampsia cespitosa subsp. cespitosa | CNPS-EB: B-PV | tufted hairgrass | |
| Gutierrezia californica | CNPS-EB: B-PV | California matchweed | |
| Layia hieracioides | CNPS-EB: B-PV | tall layia | |
| Lepidium latipes | CNPS-EB: B-PV | dwarf peppergrass | |
| Plagiobothrys acanthocarpus | CNPS-EB: B-PV | adobe popcornflower, adobe allocarya | |
| Psilocarphus brevissimus var. brevissimus | CNPS-EB: B | dwarf woollyheads, dwarf woolly-marbles | |
| Triglochin scilloides | CNPS-EB: C | flowering-quillwort |
