| | 1. Leaf upper surface densely hairy |
| |
| | 2. Calyx, corolla glandular; filaments glabrous |
| |
| | 3. Corolla 2–5 mm; calyx densely hairy, whitish |
| E. tomentosum |
| | 3' Corolla 4–9 mm; calyx ciliate to slightly hairy, dark-colored |
| E. traskiae |
| | 2' Calyx, corolla not glandular; filaments hairy |
| E. crassifolium |
| | 4. Leaf tomentose, upper surface whitish |
| var. crassifolium |
| | 4' Leaf sparsely to densely hairy, upper surface greenish |
| var. nigrescens |
| | 1' Leaf upper surface glabrous to sparsely hairy |
| |
| | 5. Leaf linear, 2–11 mm wide, generally entire (or teeth few and well separated) |
| |
| | 6. Inflorescence head-like; s Central Coast, s Outer South Coast Ranges, n South Coast, w Western Transverse Ranges (Santa Barbara Co.) |
| E. capitatum |
| | 6' Inflorescence open, spreading; s Outer South Coast Ranges, Mojave Desert (not in Santa Barbara Co.) |
| |
| | 7. Corolla 11–15 mm; s Outer South Coast Ranges (sw San Luis Obispo Co.) |
| E. altissimum |
| | 7' Corolla 3–6 mm; Mojave Desert |
| E. angustifolium |
| | 5' Leaf generally lanceolate to oblong, 5–60 mm wide, generally toothed |
| |
| | 8. Twigs generally densely hairy |
| |
| | 9. Leaf generally tomentose below, with net-like pattern |
| 2 E. crassifolium var. nigrescens |
| | 9' Leaf white-woolly below, lacking obvious net-like pattern — Peninsular Ranges, w Sonoran Desert |
| 2 E. trichocalyx var. lanatum |
| | 8' Twigs glabrous to sparsely hairy |
| |
| | 10. Corolla sparsely hairy; calyx ciliate to sparsely hairy; n California |
| E. californicum |
| | 10' Corolla densely hairy; calyx generally densely hairy; Southwestern California, Desert |
| E. trichocalyx |
| | 11. Leaf densely white-woolly below, lacking obvious net-like pattern |
| var. lanatum |
| | 11' Leaf tomentose below, with obvious net-like pattern |
| var. trichocalyx
|