| | 1. Involucral awns 5; flowers included; each perianth lobe again lobed or fringed (sect. Neoxytheca) |
| |
| | 2. Involucral bracts >> half fused; involucre very widely funnel-shaped, laterally flattened, white-margined; perianth lobes irregularly fringed; eastern Peninsular Ranges |
| O. emarginata |
| | 2' Involucral bracts << half fused; involucre funnel-shaped, not flattened or white-margined; perianth lobes with 3 ± regular lobes |
| |
| | 3. Flower 1–2 mm; s High Sierra Nevada, Transverse Ranges, San Jacinto Mountains |
| O. caryophylloides |
| | 3' Flower 2.5–4 mm; San Gabriel Mountains, San Bernardino Mountains, Peninsular Ranges, w Desert Mountains |
| O. trilobata |
| | 1' Involucral awns (3)4 or > 7; flowers exserted; perianth lobes generally entire |
| |
| | 4. Involucral awns generally 4 (mostly sect. Oxytheca) |
| |
| | 5. Bracts fully fused and completely surrounding stem; involucres sessile — s San Joaquin Valley, Great Basin Floristic Province, Mojave Desert |
| O. perfoliata |
| | 5' Bracts fused at base only; involucres nearly sessile or ± stalked |
| |
| | 6. Leaf blade obovate, ciliate, surface nearly glabrous; n San Bernardino Mountains — on limestone |
| 2 O. parishii var. goodmaniana |
| | 6' Leaf blade oblanceolate, ± hairy; Great Basin Floristic Province |
| |
| | 7. Stalks of lower involucres 2–15 mm; bract awns < 0.5 mm; Great Basin Floristic Province |
| O. dendroidea subsp. dendroidea |
| | 7' Stalks of lower involucres 0.5–2 mm throughout; bract awns > 1 mm; se White and Inyo Mountains |
| O. watsonii |
| | 4' Involucral awns 7–36 (4–5 in var. goodmaniana) (sect. Acanthoscyphus); Transverse Ranges |
| O. parishii |
| | 8. Involucral awns 7–16, reddish, longest 3–4 mm; Western Transverse Ranges |
| var. abramsii |
| | 8' Involucral awns 4–36, ivory-colored, longest generally 2–5 mm; Transverse Ranges |
| |
| | 9. Involucral awns 4–5, longest 2–3 mm; n San Bernardino Mountains, on limestone, RARE |
| var. goodmaniana |
| | 9' Involucral awns 7–36, longest 3–5 mm; Transverse Ranges, not on limestone, more common |
| |
| | 10. Involucral awns 7–10; RARE, eastern San Bernardino Mountains |
| var. cienegensis |
| | 10' Involucral awns 10–36; Transverse Ranges |
| var. parishii
|